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Remove twi library and switch to i2c library submodule

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This commit is contained in:
BlackMark 2020-05-15 11:50:11 +02:00
parent 04af54e7c8
commit 2768009720
6 changed files with 160 additions and 952 deletions
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303
rtc.cpp
View File

@ -15,7 +15,7 @@
/*
* DS1307 register map
*
*
* 00h-06h: seconds, minutes, hours, day-of-week, date, month, year (all in BCD)
* bit 7 of seconds enables/disables clock
* bit 6 of hours toggles 12/24h mode (1 for 12h, 0 for 24h)
@ -73,6 +73,11 @@
#define TRUE 1
#define FALSE 0
#include "../clock.hpp"
#include "../i2c/i2c.hpp"
using i2c_t = i2c::I2c<i2c::Hardware<100'000>>;
#include "rtc.h"
#define RTC_ADDR 0x68 // I2C address
@ -93,20 +98,23 @@ uint8_t bcd2dec(uint8_t b)
uint8_t rtc_read_byte(uint8_t offset)
{
twi_begin_transmission(RTC_ADDR);
twi_send_byte(offset);
twi_end_transmission();
i2c_t::start<RTC_ADDR>(false);
i2c_t::write(offset);
i2c_t::stop();
twi_request_from(RTC_ADDR, 1);
return twi_receive();
i2c_t::start<RTC_ADDR>(true);
const auto received = i2c_t::read<true>();
i2c_t::stop();
return received;
}
void rtc_write_byte(uint8_t b, uint8_t offset)
{
twi_begin_transmission(RTC_ADDR);
twi_send_byte(offset);
twi_send_byte(b);
twi_end_transmission();
i2c_t::start<RTC_ADDR>(false);
i2c_t::write(offset);
i2c_t::write(b);
i2c_t::stop();
}
static bool s_is_ds1307 = false;
@ -114,16 +122,18 @@ static bool s_is_ds3231 = false;
void rtc_init(void)
{
i2c_t::init();
// Attempt autodetection:
// 1) Read and save temperature register
// 2) Write a value to temperature register
// 3) Read back the value
// equal to the one written: DS1307, write back saved value and return
// different from written: DS3231
uint8_t temp1 = rtc_read_byte(0x11);
uint8_t temp2 = rtc_read_byte(0x12);
rtc_write_byte(0xee, 0x11);
rtc_write_byte(0xdd, 0x12);
@ -153,17 +163,13 @@ struct rtc_tm* rtc_get_time(void)
// read 7 bytes starting from register 0
// sec, min, hour, day-of-week, date, month, year
twi_begin_transmission(RTC_ADDR);
twi_send_byte(0x0);
twi_end_transmission();
i2c_t::start<RTC_ADDR>(false);
i2c_t::write(0x0);
i2c_t::stop();
twi_request_from(RTC_ADDR, 7);
for (uint8_t i = 0; i < 7; i++) {
rtc[i] = twi_receive();
}
twi_end_transmission();
i2c_t::start<RTC_ADDR>(true);
i2c_t::readBytes<7>(rtc);
i2c_t::stop();
// Clear clock halt bit from read data
// This starts the clock for a DS1307, and has no effect for a DS3231
@ -198,18 +204,14 @@ void rtc_get_time_s(uint8_t* hour, uint8_t* min, uint8_t* sec)
// read 7 bytes starting from register 0
// sec, min, hour, day-of-week, date, month, year
twi_begin_transmission(RTC_ADDR);
twi_send_byte(0x0);
twi_end_transmission();
twi_request_from(RTC_ADDR, 7);
for(uint8_t i=0; i<7; i++) {
rtc[i] = twi_receive();
}
twi_end_transmission();
i2c_t::start<RTC_ADDR>(false);
i2c_t::write(0x0);
i2c_t::stop();
i2c_t::start<RTC_ADDR>(true);
i2c_t::readBytes<7>(rtc);
i2c_t::stop();
if (sec) *sec = bcd2dec(rtc[0]);
if (min) *min = bcd2dec(rtc[1]);
if (hour) *hour = bcd2dec(rtc[2]);
@ -218,8 +220,8 @@ void rtc_get_time_s(uint8_t* hour, uint8_t* min, uint8_t* sec)
// fixme: support 12-hour mode for setting time
void rtc_set_time(struct rtc_tm* tm_)
{
twi_begin_transmission(RTC_ADDR);
twi_send_byte(0x0);
i2c_t::start<RTC_ADDR>(false);
i2c_t::write(0x0);
uint8_t century;
if (tm_->year > 2000) {
@ -231,28 +233,28 @@ void rtc_set_time(struct rtc_tm* tm_)
}
// clock halt bit is 7th bit of seconds: this is always cleared to start the clock
twi_send_byte(dec2bcd(tm_->sec)); // seconds
twi_send_byte(dec2bcd(tm_->min)); // minutes
twi_send_byte(dec2bcd(tm_->hour)); // hours
twi_send_byte(dec2bcd(tm_->wday)); // day of week
twi_send_byte(dec2bcd(tm_->mday)); // day
twi_send_byte(dec2bcd(tm_->mon) + century); // month
twi_send_byte(dec2bcd(tm_->year)); // year
i2c_t::write(dec2bcd(tm_->sec)); // seconds
i2c_t::write(dec2bcd(tm_->min)); // minutes
i2c_t::write(dec2bcd(tm_->hour)); // hours
i2c_t::write(dec2bcd(tm_->wday)); // day of week
i2c_t::write(dec2bcd(tm_->mday)); // day
i2c_t::write(dec2bcd(tm_->mon) + century); // month
i2c_t::write(dec2bcd(tm_->year)); // year
twi_end_transmission();
i2c_t::stop();
}
void rtc_set_time_s(uint8_t hour, uint8_t min, uint8_t sec)
{
twi_begin_transmission(RTC_ADDR);
twi_send_byte(0x0);
i2c_t::start<RTC_ADDR>(false);
i2c_t::write(0x0);
// clock halt bit is 7th bit of seconds: this is always cleared to start the clock
twi_send_byte(dec2bcd(sec)); // seconds
twi_send_byte(dec2bcd(min)); // minutes
twi_send_byte(dec2bcd(hour)); // hours
twi_end_transmission();
i2c_t::write(dec2bcd(sec)); // seconds
i2c_t::write(dec2bcd(min)); // minutes
i2c_t::write(dec2bcd(hour)); // hours
i2c_t::stop();
}
// DS1307 only (has no effect when run on DS3231)
@ -263,14 +265,14 @@ void rtc_set_time_s(uint8_t hour, uint8_t min, uint8_t sec)
void rtc_run_clock(bool run)
{
if (s_is_ds3231) return;
uint8_t b = rtc_read_byte(0x0);
if (run)
b &= ~(_BV(CH_BIT)); // clear bit
else
b |= _BV(CH_BIT); // set bit
rtc_write_byte(b, 0x0);
}
@ -280,7 +282,7 @@ void rtc_run_clock(bool run)
bool rtc_is_clock_running(void)
{
if (s_is_ds3231) return true;
uint8_t b = rtc_read_byte(0x0);
if (b & _BV(CH_BIT)) return false;
@ -290,31 +292,28 @@ bool rtc_is_clock_running(void)
void ds3231_get_temp_int(int8_t* i, uint8_t* f)
{
uint8_t msb, lsb;
*i = 0;
*f = 0;
if (s_is_ds1307) return; // only valid on DS3231
twi_begin_transmission(RTC_ADDR);
i2c_t::start<RTC_ADDR>(false);
// temp registers 0x11 and 0x12
twi_send_byte(0x11);
twi_end_transmission();
i2c_t::write(0x11);
i2c_t::stop();
twi_request_from(RTC_ADDR, 2);
i2c_t::start<RTC_ADDR>(true);
msb = i2c_t::read(); // integer part (in twos complement)
lsb = i2c_t::read<true>(); // fraction part
if (twi_available()) {
msb = twi_receive(); // integer part (in twos complement)
lsb = twi_receive(); // fraction part
// integer part in entire byte
*i = msb;
// fractional part in top two bits (increments of 0.25)
*f = (lsb >> 6) * 25;
// integer part in entire byte
*i = msb;
// fractional part in top two bits (increments of 0.25)
*f = (lsb >> 6) * 25;
// float value can be read like so:
// float temp = ((((short)msb << 8) | (short)lsb) >> 6) / 4.0f;
}
// float value can be read like so:
// float temp = ((((short)msb << 8) | (short)lsb) >> 6) / 4.0f;
}
void rtc_force_temp_conversion(uint8_t block)
@ -322,31 +321,34 @@ void rtc_force_temp_conversion(uint8_t block)
if (s_is_ds1307) return; // only valid on DS3231
// read control register (0x0E)
twi_begin_transmission(RTC_ADDR);
twi_send_byte(0x0E);
twi_end_transmission();
i2c_t::start<RTC_ADDR>(false);
i2c_t::write(0x0E);
i2c_t::stop();
twi_request_from(RTC_ADDR, 1);
uint8_t ctrl = twi_receive();
i2c_t::start<RTC_ADDR>(true);
uint8_t ctrl = i2c_t::read<true>();
i2c_t::stop();
ctrl |= 0b00100000; // Set CONV bit
// write new control register value
twi_begin_transmission(RTC_ADDR);
twi_send_byte(0x0E);
twi_send_byte(ctrl);
twi_end_transmission();
i2c_t::start<RTC_ADDR>(false);
i2c_t::write(0x0E);
i2c_t::write(ctrl);
i2c_t::stop();
if (!block) return;
// Temp conversion is ready when control register becomes 0
do {
// Block until CONV is 0
twi_begin_transmission(RTC_ADDR);
twi_send_byte(0x0E);
twi_end_transmission();
twi_request_from(RTC_ADDR, 1);
} while ((twi_receive() & 0b00100000) != 0);
i2c_t::start<RTC_ADDR>(false);
i2c_t::write(0x0E);
i2c_t::stop();
i2c_t::start<RTC_ADDR>(true);
// HACK: Missing stop after read, might still work though
} while ((i2c_t::read<true>() & 0b00100000) != 0);
}
@ -371,32 +373,35 @@ void rtc_set_sram(uint8_t *data)
uint8_t rtc_get_sram_byte(uint8_t offset)
{
twi_begin_transmission(RTC_ADDR);
twi_send_byte(DS1307_SRAM_ADDR + offset);
twi_end_transmission();
i2c_t::start<RTC_ADDR>(false);
i2c_t::write(DS1307_SRAM_ADDR + offset);
i2c_t::stop();
twi_request_from(RTC_ADDR, 1);
return twi_receive();
i2c_t::start<RTC_ADDR>(true);
const auto received = i2c_t::read<true>();
i2c_t::stop();
return received;
}
void rtc_set_sram_byte(uint8_t b, uint8_t offset)
{
twi_begin_transmission(RTC_ADDR);
twi_send_byte(DS1307_SRAM_ADDR + offset);
twi_send_byte(b);
twi_end_transmission();
i2c_t::start<RTC_ADDR>(false);
i2c_t::write(DS1307_SRAM_ADDR + offset);
i2c_t::write(b);
i2c_t::stop();
}
void rtc_SQW_enable(bool enable)
{
if (s_is_ds1307) {
twi_begin_transmission(RTC_ADDR);
twi_send_byte(0x07);
twi_end_transmission();
i2c_t::start<RTC_ADDR>(false);
i2c_t::write(0x07);
i2c_t::stop();
// read control
twi_request_from(RTC_ADDR, 1);
uint8_t control = twi_receive();
i2c_t::start<RTC_ADDR>(true);
uint8_t control = i2c_t::read<true>();
i2c_t::stop();
if (enable)
control |= 0b00010000; // set SQWE to 1
@ -404,20 +409,21 @@ void rtc_SQW_enable(bool enable)
control &= ~0b00010000; // set SQWE to 0
// write control back
twi_begin_transmission(RTC_ADDR);
twi_send_byte(0x07);
twi_send_byte(control);
twi_end_transmission();
i2c_t::start<RTC_ADDR>(false);
i2c_t::write(0x07);
i2c_t::write(control);
i2c_t::stop();
}
else { // DS3231
twi_begin_transmission(RTC_ADDR);
twi_send_byte(0x0E);
twi_end_transmission();
i2c_t::start<RTC_ADDR>(false);
i2c_t::write(0x0E);
i2c_t::stop();
// read control
twi_request_from(RTC_ADDR, 1);
uint8_t control = twi_receive();
i2c_t::start<RTC_ADDR>(true);
uint8_t control = i2c_t::read<true>();
i2c_t::stop();
if (enable) {
control |= 0b01000000; // set BBSQW to 1
@ -428,51 +434,53 @@ void rtc_SQW_enable(bool enable)
}
// write control back
twi_begin_transmission(RTC_ADDR);
twi_send_byte(0x0E);
twi_send_byte(control);
twi_end_transmission();
i2c_t::start<RTC_ADDR>(false);
i2c_t::write(0x0E);
i2c_t::write(control);
i2c_t::stop();
}
}
void rtc_SQW_set_freq(enum RTC_SQW_FREQ freq)
{
if (s_is_ds1307) {
twi_begin_transmission(RTC_ADDR);
twi_send_byte(0x07);
twi_end_transmission();
i2c_t::start<RTC_ADDR>(false);
i2c_t::write(0x07);
i2c_t::stop();
// read control (uses bits 0 and 1)
twi_request_from(RTC_ADDR, 1);
uint8_t control = twi_receive();
i2c_t::start<RTC_ADDR>(true);
uint8_t control = i2c_t::read<true>();
i2c_t::stop();
control &= ~0b00000011; // Set to 0
control |= freq; // Set freq bitmask
// write control back
twi_begin_transmission(RTC_ADDR);
twi_send_byte(0x07);
twi_send_byte(control);
twi_end_transmission();
i2c_t::start<RTC_ADDR>(false);
i2c_t::write(0x07);
i2c_t::write(control);
i2c_t::stop();
}
else { // DS3231
twi_begin_transmission(RTC_ADDR);
twi_send_byte(0x0E);
twi_end_transmission();
i2c_t::start<RTC_ADDR>(false);
i2c_t::write(0x0E);
i2c_t::stop();
// read control (uses bits 3 and 4)
twi_request_from(RTC_ADDR, 1);
uint8_t control = twi_receive();
i2c_t::start<RTC_ADDR>(true);
uint8_t control = i2c_t::read<true>();
i2c_t::stop();
control &= ~0b00011000; // Set to 0
control |= (freq << 4); // Set freq bitmask
// write control back
twi_begin_transmission(RTC_ADDR);
twi_send_byte(0x0E);
twi_send_byte(control);
twi_end_transmission();
i2c_t::start<RTC_ADDR>(false);
i2c_t::write(0x0E);
i2c_t::write(control);
i2c_t::stop();
}
}
@ -480,13 +488,14 @@ void rtc_osc32kHz_enable(bool enable)
{
if (!s_is_ds3231) return;
twi_begin_transmission(RTC_ADDR);
twi_send_byte(0x0F);
twi_end_transmission();
i2c_t::start<RTC_ADDR>(false);
i2c_t::write(0x0F);
i2c_t::stop();
// read status
twi_request_from(RTC_ADDR, 1);
uint8_t status = twi_receive();
i2c_t::start<RTC_ADDR>(true);
uint8_t status = i2c_t::read<true>();
i2c_t::stop();
if (enable)
status |= 0b00001000; // set to 1
@ -494,14 +503,14 @@ void rtc_osc32kHz_enable(bool enable)
status &= ~0b00001000; // Set to 0
// write status back
twi_begin_transmission(RTC_ADDR);
twi_send_byte(0x0F);
twi_send_byte(status);
twi_end_transmission();
i2c_t::start<RTC_ADDR>(false);
i2c_t::write(0x0F);
i2c_t::write(status);
i2c_t::stop();
}
// Alarm functionality
// fixme: should decide if "alarm disabled" mode should be available, or if alarm should always be enabled
// fixme: should decide if "alarm disabled" mode should be available, or if alarm should always be enabled
// at 00:00:00. Currently, "alarm disabled" only works for ds3231
void rtc_reset_alarm(void)
{
@ -590,7 +599,7 @@ bool rtc_check_alarm(void)
uint8_t cur_hour, cur_min, cur_sec;
rtc_get_time_s(&cur_hour, &cur_min, &cur_sec);
if (cur_hour == hour && cur_min == min && cur_sec == sec)
return true;
return false;
@ -602,7 +611,7 @@ bool rtc_check_alarm(void)
// clear flag when set
if (val & 1)
rtc_write_byte(val & ~0b00000001, 0x0f);
return val & 1 ? 1 : 0;
}
}

9
rtc.h
View File

@ -18,14 +18,13 @@
#include <stdbool.h>
#include <avr/io.h>
#include "twi.h"
#define DS1307_SLAVE_ADDR 0b11010000
/** Time structure
*
*
* Both 24-hour and 12-hour time is stored, and is always updated when rtc_get_time is called.
*
*
* When setting time and alarm, 24-hour mode is always used.
*
* If you run your clock in 12-hour mode:
@ -52,7 +51,7 @@ struct rtc_tm {
int twelveHour; // 12 hour clock time
};
// statically allocated
// statically allocated
extern struct rtc_tm _rtc_tm;
// Initialize the RTC and autodetect type (DS1307 or DS3231)
@ -102,6 +101,6 @@ void rtc_set_alarm(struct rtc_tm* tm_);
void rtc_set_alarm_s(uint8_t hour, uint8_t min, uint8_t sec);
struct rtc_tm* rtc_get_alarm(void);
void rtc_get_alarm_s(uint8_t* hour, uint8_t* min, uint8_t* sec);
bool rtc_check_alarm(void);
bool rtc_check_alarm(void);
#endif

479
twi-lowlevel.cpp
View File

@ -1,479 +0,0 @@
/*
twi.c - TWI/I2C library for Wiring & Arduino
Copyright (c) 2006 Nicholas Zambetti. All right reserved.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <math.h>
#include <stdlib.h>
#include <inttypes.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#include <compat/twi.h>
#ifndef cbi
#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
#endif
#ifndef sbi
#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
#endif
#include "twi-lowlevel.h"
static volatile uint8_t twi_state;
static uint8_t twi_slarw;
static void (*twi_onSlaveTransmit)(void);
static void (*twi_onSlaveReceive)(uint8_t*, int);
static uint8_t twi_masterBuffer[TWI_BUFFER_LENGTH];
static volatile uint8_t twi_masterBufferIndex;
static uint8_t twi_masterBufferLength;
static uint8_t twi_txBuffer[TWI_BUFFER_LENGTH];
static volatile uint8_t twi_txBufferIndex;
static volatile uint8_t twi_txBufferLength;
static uint8_t twi_rxBuffer[TWI_BUFFER_LENGTH];
static volatile uint8_t twi_rxBufferIndex;
static volatile uint8_t twi_error;
/*
* Function twi_init
* Desc readys twi pins and sets twi bitrate
* Input none
* Output none
*/
void twi_init(void)
{
// initialize state
twi_state = TWI_READY;
#if defined(__AVR_ATmega168__) || defined(__AVR_ATmega8__) || defined(__AVR_ATmega328P__)
// activate internal pull-ups for twi
// as per note from atmega8 manual pg167
sbi(PORTC, 4);
sbi(PORTC, 5);
#else
// activate internal pull-ups for twi
// as per note from atmega128 manual pg204
sbi(PORTD, 0);
sbi(PORTD, 1);
#endif
// initialize twi prescaler and bit rate
cbi(TWSR, TWPS0);
cbi(TWSR, TWPS1);
TWBR = ((F_CPU / TWI_FREQ) - 16) / 2;
/* twi bit rate formula from atmega128 manual pg 204
SCL Frequency = CPU Clock Frequency / (16 + (2 * TWBR))
note: TWBR should be 10 or higher for master mode
It is 72 for a 16mhz Wiring board with 100kHz TWI */
// enable twi module, acks, and twi interrupt
TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA);
}
/*
* Function twi_slaveInit
* Desc sets slave address and enables interrupt
* Input none
* Output none
*/
void twi_setAddress(uint8_t address)
{
// set twi slave address (skip over TWGCE bit)
TWAR = address << 1;
}
/*
* Function twi_readFrom
* Desc attempts to become twi bus master and read a
* series of bytes from a device on the bus
* Input address: 7bit i2c device address
* data: pointer to byte array
* length: number of bytes to read into array
* Output number of bytes read
*/
uint8_t twi_readFrom(uint8_t address, uint8_t* data, uint8_t length)
{
uint8_t i;
// ensure data will fit into buffer
if(TWI_BUFFER_LENGTH < length){
return 0;
}
// wait until twi is ready, become master receiver
while(TWI_READY != twi_state){
continue;
}
twi_state = TWI_MRX;
// reset error state (0xFF.. no error occured)
twi_error = 0xFF;
// initialize buffer iteration vars
twi_masterBufferIndex = 0;
twi_masterBufferLength = length-1; // This is not intuitive, read on...
// On receive, the previously configured ACK/NACK setting is transmitted in
// response to the received byte before the interrupt is signalled.
// Therefor we must actually set NACK when the _next_ to last byte is
// received, causing that NACK to be sent in response to receiving the last
// expected byte of data.
// build sla+w, slave device address + w bit
twi_slarw = TW_READ;
twi_slarw |= address << 1;
// send start condition
TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT) | _BV(TWSTA);
// wait for read operation to complete
while(TWI_MRX == twi_state){
continue;
}
if (twi_masterBufferIndex < length)
length = twi_masterBufferIndex;
// copy twi buffer to data
for(i = 0; i < length; ++i){
data[i] = twi_masterBuffer[i];
}
return length;
}
/*
* Function twi_writeTo
* Desc attempts to become twi bus master and write a
* series of bytes to a device on the bus
* Input address: 7bit i2c device address
* data: pointer to byte array
* length: number of bytes in array
* wait: boolean indicating to wait for write or not
* Output 0 .. success
* 1 .. length to long for buffer
* 2 .. address send, NACK received
* 3 .. data send, NACK received
* 4 .. other twi error (lost bus arbitration, bus error, ..)
*/
uint8_t twi_writeTo(uint8_t address, uint8_t* data, uint8_t length, uint8_t wait)
{
uint8_t i;
// ensure data will fit into buffer
if(TWI_BUFFER_LENGTH < length){
return 1;
}
// wait until twi is ready, become master transmitter
while(TWI_READY != twi_state){
continue;
}
twi_state = TWI_MTX;
// reset error state (0xFF.. no error occured)
twi_error = 0xFF;
// initialize buffer iteration vars
twi_masterBufferIndex = 0;
twi_masterBufferLength = length;
// copy data to twi buffer
for(i = 0; i < length; ++i){
twi_masterBuffer[i] = data[i];
}
// build sla+w, slave device address + w bit
twi_slarw = TW_WRITE;
twi_slarw |= address << 1;
// send start condition
TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT) | _BV(TWSTA);
// wait for write operation to complete
while(wait && (TWI_MTX == twi_state)){
continue;
}
if (twi_error == 0xFF)
return 0; // success
else if (twi_error == TW_MT_SLA_NACK)
return 2; // error: address send, nack received
else if (twi_error == TW_MT_DATA_NACK)
return 3; // error: data send, nack received
else
return 4; // other twi error
}
/*
* Function twi_transmit
* Desc fills slave tx buffer with data
* must be called in slave tx event callback
* Input data: pointer to byte array
* length: number of bytes in array
* Output 1 length too long for buffer
* 2 not slave transmitter
* 0 ok
*/
uint8_t twi_transmit(uint8_t* data, uint8_t length)
{
uint8_t i;
// ensure data will fit into buffer
if(TWI_BUFFER_LENGTH < length){
return 1;
}
// ensure we are currently a slave transmitter
if(TWI_STX != twi_state){
return 2;
}
// set length and copy data into tx buffer
twi_txBufferLength = length;
for(i = 0; i < length; ++i){
twi_txBuffer[i] = data[i];
}
return 0;
}
/*
* Function twi_attachSlaveRxEvent
* Desc sets function called before a slave read operation
* Input function: callback function to use
* Output none
*/
void twi_attachSlaveRxEvent( void (*function)(uint8_t*, int) )
{
twi_onSlaveReceive = function;
}
/*
* Function twi_attachSlaveTxEvent
* Desc sets function called before a slave write operation
* Input function: callback function to use
* Output none
*/
void twi_attachSlaveTxEvent( void (*function)(void) )
{
twi_onSlaveTransmit = function;
}
/*
* Function twi_reply
* Desc sends byte or readys receive line
* Input ack: byte indicating to ack or to nack
* Output none
*/
void twi_reply(uint8_t ack)
{
// transmit master read ready signal, with or without ack
if(ack){
TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWINT) | _BV(TWEA);
}else{
TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWINT);
}
}
/*
* Function twi_stop
* Desc relinquishes bus master status
* Input none
* Output none
*/
void twi_stop(void)
{
// send stop condition
TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT) | _BV(TWSTO);
// wait for stop condition to be exectued on bus
// TWINT is not set after a stop condition!
while(TWCR & _BV(TWSTO)){
continue;
}
// update twi state
twi_state = TWI_READY;
}
/*
* Function twi_releaseBus
* Desc releases bus control
* Input none
* Output none
*/
void twi_releaseBus(void)
{
// release bus
TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT);
// update twi state
twi_state = TWI_READY;
}
SIGNAL(TWI_vect)
{
switch(TW_STATUS){
// All Master
case TW_START: // sent start condition
case TW_REP_START: // sent repeated start condition
// copy device address and r/w bit to output register and ack
TWDR = twi_slarw;
twi_reply(1);
break;
// Master Transmitter
case TW_MT_SLA_ACK: // slave receiver acked address
case TW_MT_DATA_ACK: // slave receiver acked data
// if there is data to send, send it, otherwise stop
if(twi_masterBufferIndex < twi_masterBufferLength){
// copy data to output register and ack
TWDR = twi_masterBuffer[twi_masterBufferIndex++];
twi_reply(1);
}else{
twi_stop();
}
break;
case TW_MT_SLA_NACK: // address sent, nack received
twi_error = TW_MT_SLA_NACK;
twi_stop();
break;
case TW_MT_DATA_NACK: // data sent, nack received
twi_error = TW_MT_DATA_NACK;
twi_stop();
break;
case TW_MT_ARB_LOST: // lost bus arbitration
twi_error = TW_MT_ARB_LOST;
twi_releaseBus();
break;
// Master Receiver
case TW_MR_DATA_ACK: // data received, ack sent
// put byte into buffer
twi_masterBuffer[twi_masterBufferIndex++] = TWDR;
[[fallthrough]];
case TW_MR_SLA_ACK: // address sent, ack received
// ack if more bytes are expected, otherwise nack
if(twi_masterBufferIndex < twi_masterBufferLength){
twi_reply(1);
}else{
twi_reply(0);
}
break;
case TW_MR_DATA_NACK: // data received, nack sent
// put final byte into buffer
twi_masterBuffer[twi_masterBufferIndex++] = TWDR;
[[fallthrough]];
case TW_MR_SLA_NACK: // address sent, nack received
twi_stop();
break;
// TW_MR_ARB_LOST handled by TW_MT_ARB_LOST case
// Slave Receiver
case TW_SR_SLA_ACK: // addressed, returned ack
case TW_SR_GCALL_ACK: // addressed generally, returned ack
case TW_SR_ARB_LOST_SLA_ACK: // lost arbitration, returned ack
case TW_SR_ARB_LOST_GCALL_ACK: // lost arbitration, returned ack
// enter slave receiver mode
twi_state = TWI_SRX;
// indicate that rx buffer can be overwritten and ack
twi_rxBufferIndex = 0;
twi_reply(1);
break;
case TW_SR_DATA_ACK: // data received, returned ack
case TW_SR_GCALL_DATA_ACK: // data received generally, returned ack
// if there is still room in the rx buffer
if(twi_rxBufferIndex < TWI_BUFFER_LENGTH){
// put byte in buffer and ack
twi_rxBuffer[twi_rxBufferIndex++] = TWDR;
twi_reply(1);
}else{
// otherwise nack
twi_reply(0);
}
break;
case TW_SR_STOP: // stop or repeated start condition received
// put a null char after data if there's room
if(twi_rxBufferIndex < TWI_BUFFER_LENGTH){
twi_rxBuffer[twi_rxBufferIndex] = '\0';
}
// sends ack and stops interface for clock stretching
twi_stop();
// callback to user defined callback
twi_onSlaveReceive(twi_rxBuffer, twi_rxBufferIndex);
// since we submit rx buffer to "wire" library, we can reset it
twi_rxBufferIndex = 0;
// ack future responses and leave slave receiver state
twi_releaseBus();
break;
case TW_SR_DATA_NACK: // data received, returned nack
case TW_SR_GCALL_DATA_NACK: // data received generally, returned nack
// nack back at master
twi_reply(0);
break;
// Slave Transmitter
case TW_ST_SLA_ACK: // addressed, returned ack
case TW_ST_ARB_LOST_SLA_ACK: // arbitration lost, returned ack
// enter slave transmitter mode
twi_state = TWI_STX;
// ready the tx buffer index for iteration
twi_txBufferIndex = 0;
// set tx buffer length to be zero, to verify if user changes it
twi_txBufferLength = 0;
// request for txBuffer to be filled and length to be set
// note: user must call twi_transmit(bytes, length) to do this
twi_onSlaveTransmit();
// if they didn't change buffer & length, initialize it
if(0 == twi_txBufferLength){
twi_txBufferLength = 1;
twi_txBuffer[0] = 0x00;
}
// transmit first byte from buffer, fall
[[fallthrough]];
case TW_ST_DATA_ACK: // byte sent, ack returned
// copy data to output register
TWDR = twi_txBuffer[twi_txBufferIndex++];
// if there is more to send, ack, otherwise nack
if(twi_txBufferIndex < twi_txBufferLength){
twi_reply(1);
}else{
twi_reply(0);
}
break;
case TW_ST_DATA_NACK: // received nack, we are done
case TW_ST_LAST_DATA: // received ack, but we are done already!
// ack future responses
twi_reply(1);
// leave slave receiver state
twi_state = TWI_READY;
break;
// All
case TW_NO_INFO: // no state information
break;
case TW_BUS_ERROR: // bus error, illegal stop/start
twi_error = TW_BUS_ERROR;
twi_stop();
break;
}
}

55
twi-lowlevel.h
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@ -1,55 +0,0 @@
/*
twi.h - TWI/I2C library for Wiring & Arduino
Copyright (c) 2006 Nicholas Zambetti. All right reserved.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef twi_h
#define twi_h
#include <inttypes.h>
#include "../clock.hpp"
//#define ATMEGA8
#ifndef TWI_FREQ
#define TWI_FREQ 100000L
#endif
#ifndef TWI_BUFFER_LENGTH
#define TWI_BUFFER_LENGTH 32
#endif
#define TWI_READY 0
#define TWI_MRX 1
#define TWI_MTX 2
#define TWI_SRX 3
#define TWI_STX 4
void twi_init(void);
void twi_setAddress(uint8_t);
uint8_t twi_readFrom(uint8_t, uint8_t*, uint8_t);
uint8_t twi_writeTo(uint8_t, uint8_t*, uint8_t, uint8_t);
uint8_t twi_transmit(uint8_t*, uint8_t);
void twi_attachSlaveRxEvent( void (*)(uint8_t*, int) );
void twi_attachSlaveTxEvent( void (*)(void) );
void twi_reply(uint8_t);
void twi_stop(void);
void twi_releaseBus(void);
#endif

226
twi.cpp
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/*
TwoWire.cpp - TWI/I2C library for Wiring & Arduino
Copyright (c) 2006 Nicholas Zambetti. All right reserved.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdlib.h>
#include <string.h>
#include <inttypes.h>
#include "twi-lowlevel.h"
#include "twi.h"
// local variables
uint8_t rxBuffer[BUFFER_LENGTH];
uint8_t rxBufferIndex = 0;
uint8_t rxBufferLength = 0;
uint8_t txAddress = 0;
uint8_t txBuffer[BUFFER_LENGTH];
uint8_t txBufferIndex = 0;
uint8_t txBufferLength = 0;
uint8_t transmitting = 0;
void (*user_onRequest)(void);
void (*user_onReceive)(int);
void onRequestService(void);
void onReceiveService(uint8_t*, int);
void twi_init_master(void)
{
rxBufferIndex = 0;
rxBufferLength = 0;
txBufferIndex = 0;
txBufferLength = 0;
twi_init();
}
void twi_init_slave(uint8_t address)
{
twi_setAddress(address);
twi_attachSlaveTxEvent(onRequestService);
twi_attachSlaveRxEvent(onReceiveService);
twi_init_master();
}
uint8_t twi_request_from(uint8_t address, uint8_t quantity)
{
// clamp to buffer length
if(quantity > BUFFER_LENGTH){
quantity = BUFFER_LENGTH;
}
// perform blocking read into buffer
uint8_t read = twi_readFrom(address, rxBuffer, quantity);
// set rx buffer iterator vars
rxBufferIndex = 0;
rxBufferLength = read;
return read;
}
void twi_begin_transmission(uint8_t address)
{
// indicate that we are transmitting
transmitting = 1;
// set address of targeted slave
txAddress = address;
// reset tx buffer iterator vars
txBufferIndex = 0;
txBufferLength = 0;
}
uint8_t twi_end_transmission(void)
{
// transmit buffer (blocking)
int8_t ret = twi_writeTo(txAddress, txBuffer, txBufferLength, 1);
// reset tx buffer iterator vars
txBufferIndex = 0;
txBufferLength = 0;
// indicate that we are done transmitting
transmitting = 0;
return ret;
}
// must be called in:
// slave tx event callback
// or after beginTransmission(address)
void twi_send_byte(uint8_t data)
{
if(transmitting){
// in master transmitter mode
// don't bother if buffer is full
if(txBufferLength >= BUFFER_LENGTH){
return;
}
// put byte in tx buffer
txBuffer[txBufferIndex] = data;
++txBufferIndex;
// update amount in buffer
txBufferLength = txBufferIndex;
}else{
// in slave send mode
// reply to master
twi_transmit(&data, 1);
}
}
// must be called in:
// slave tx event callback
// or after beginTransmission(address)
void twi_send(uint8_t* data, uint8_t quantity)
{
if(transmitting){
// in master transmitter mode
for(uint8_t i = 0; i < quantity; ++i){
twi_send_byte(data[i]);
}
}else{
// in slave send mode
// reply to master
twi_transmit(data, quantity);
}
}
// must be called in:
// slave tx event callback
// or after beginTransmission(address)
void twi_send_char(char* data)
{
twi_send((uint8_t*)data, strlen(data));
}
// must be called in:
// slave rx event callback
// or after requestFrom(address, numBytes)
uint8_t twi_available(void)
{
return rxBufferLength - rxBufferIndex;
}
// must be called in:
// slave rx event callback
// or after requestFrom(address, numBytes)
uint8_t twi_receive(void)
{
// default to returning null char
// for people using with char strings
uint8_t value = '\0';
// get each successive byte on each call
if(rxBufferIndex < rxBufferLength){
value = rxBuffer[rxBufferIndex];
++rxBufferIndex;
}
return value;
}
// behind the scenes function that is called when data is received
void onReceiveService(uint8_t* inBytes, int numBytes)
{
// don't bother if user hasn't registered a callback
if(!user_onReceive){
return;
}
// don't bother if rx buffer is in use by a master requestFrom() op
// i know this drops data, but it allows for slight stupidity
// meaning, they may not have read all the master requestFrom() data yet
if(rxBufferIndex < rxBufferLength){
return;
}
// copy twi rx buffer into local read buffer
// this enables new reads to happen in parallel
for(uint8_t i = 0; i < numBytes; ++i){
rxBuffer[i] = inBytes[i];
}
// set rx iterator vars
rxBufferIndex = 0;
rxBufferLength = numBytes;
// alert user program
user_onReceive(numBytes);
}
// behind the scenes function that is called when data is requested
void onRequestService(void)
{
// don't bother if user hasn't registered a callback
if(!user_onRequest){
return;
}
// reset tx buffer iterator vars
// !!! this will kill any pending pre-master sendTo() activity
txBufferIndex = 0;
txBufferLength = 0;
// alert user program
user_onRequest();
}
// sets function called on slave write
void twi_set_on_receive( void (*function)(int) )
{
user_onReceive = function;
}
// sets function called on slave read
void twi_set_on_request( void (*function)(void) )
{
user_onRequest = function;
}

40
twi.h
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@ -1,40 +0,0 @@
/*
TwoWire.h - TWI/I2C library for Arduino & Wiring
Copyright (c) 2006 Nicholas Zambetti. All right reserved.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef TwoWire_h
#define TwoWire_h
#include <inttypes.h>
#define BUFFER_LENGTH 32
void twi_init_master(void);
void twi_init_slave(uint8_t);
void twi_begin_transmission(uint8_t);
uint8_t twi_end_transmission(void);
uint8_t twi_request_from(uint8_t, uint8_t);
void twi_send_byte(uint8_t);
void twi_send(uint8_t*, uint8_t);
void twi_send_char(char*);
uint8_t twi_available(void);
uint8_t twi_receive(void);
void twi_set_on_receive( void (*)(int) );
void twi_set_on_request( void (*)(void) );
#endif