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3 Commits
master ... example

Author SHA1 Message Date
BlackMark
3eb298053b Made prescaler automatic 2020-02-21 16:32:39 +01:00
BlackMark
e82fb9971e Implemented usage example 2020-02-21 15:10:45 +01:00
BlackMark
4075cb4e63 Created basic example 2020-02-21 13:57:57 +01:00
9 changed files with 260 additions and 189 deletions
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3
.gitmodules vendored Normal file
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[submodule "i2c/i2c"]
path = i2c/i2c
url = git@git.blackmark.me:avr/i2c.git

2
LICENSE
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MIT License
Copyright (c) 2019 BlackMark
Copyright (c) 2020 BlackMark
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal

126
hardware.hpp
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#pragma once
#include <stdint.h>
#include <util/twi.h>
namespace i2c {
#if defined(__AVR_ATmega1284P__) || defined(__AVR_ATmega328P__)
template <uint32_t Clock>
class Hardware {
public:
static void init()
{
constexpr auto clock = calcClock();
static_assert(checkClock(clock), "Unable to set requested I2C frequency");
TWSR = clock.prescaler;
TWBR = clock.bitrate;
}
template <uint8_t Addr>
static bool start(bool read)
{
TWCR = (1 << TWINT) | (1 << TWSTA) | (1 << TWEN);
while (!(TWCR & (1 << TWINT)))
;
uint8_t status = TW_STATUS & 0xF8;
if (status != TW_START && status != TW_REP_START)
return false;
TWDR = (Addr << 1) | read;
TWCR = (1 << TWINT) | (1 << TWEN);
while (!(TWCR & (1 << TWINT)))
;
status = TW_STATUS & 0xF8;
if (status != TW_MT_SLA_ACK && status != TW_MR_SLA_ACK)
return false;
return true;
}
static bool write(uint8_t data)
{
TWDR = data;
TWCR = (1 << TWINT) | (1 << TWEN);
while (!(TWCR & (1 << TWINT)))
;
uint8_t status = TW_STATUS & 0xF8;
if (status != TW_MT_DATA_ACK)
return false;
return true;
}
template <bool LastByte = false>
static uint8_t read()
{
TWCR = (1 << TWINT) | (1 << TWEN) | (!LastByte << TWEA);
while (!(TWCR & (1 << TWINT)))
;
return TWDR;
}
static void stop()
{
TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);
while (TWCR & (1 << TWSTO))
;
}
private:
struct ClockCfg {
uint8_t prescaler;
uint8_t bitrate;
};
static constexpr auto calcScl(ClockCfg clk)
{
return F_CPU / (16 + 2 * clk.bitrate * clk.prescaler);
}
static constexpr auto checkClock(ClockCfg clk)
{
constexpr auto constexprAbs = [](auto val) {
if (val < 0)
return -val;
return val;
};
constexpr auto CLOCK_EPSILON = 10;
auto scl = calcScl(clk);
if (constexprAbs(static_cast<int>(scl) - static_cast<int>(Clock)) < CLOCK_EPSILON)
return true;
return false;
}
static constexpr auto calcClock()
{
constexpr auto calcBitRate = [](uint8_t prescaler) { return (F_CPU / Clock - 16) / (2 * prescaler); };
auto clk = ClockCfg{1, 0};
for (uint8_t prescaler = 1; prescaler <= 64; prescaler *= 4) {
clk.prescaler = prescaler;
clk.bitrate = calcBitRate(prescaler);
if (checkClock(clk))
break;
}
return clk;
}
};
#endif
} // namespace i2c

22
i2c.atsln Normal file
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Microsoft Visual Studio Solution File, Format Version 12.00
# Atmel Studio Solution File, Format Version 11.00
VisualStudioVersion = 14.0.23107.0
MinimumVisualStudioVersion = 10.0.40219.1
Project("{E66E83B9-2572-4076-B26E-6BE79FF3018A}") = "i2c", "i2c\i2c.cppproj", "{DCE6C7E3-EE26-4D79-826B-08594B9AD897}"
EndProject
Global
GlobalSection(SolutionConfigurationPlatforms) = preSolution
Debug|AVR = Debug|AVR
Release|AVR = Release|AVR
EndGlobalSection
GlobalSection(ProjectConfigurationPlatforms) = postSolution
{DCE6C7E3-EE26-4D79-826B-08594B9AD897}.Debug|AVR.ActiveCfg = Debug|AVR
{DCE6C7E3-EE26-4D79-826B-08594B9AD897}.Debug|AVR.Build.0 = Debug|AVR
{DCE6C7E3-EE26-4D79-826B-08594B9AD897}.Release|AVR.ActiveCfg = Release|AVR
{DCE6C7E3-EE26-4D79-826B-08594B9AD897}.Release|AVR.Build.0 = Release|AVR
EndGlobalSection
GlobalSection(SolutionProperties) = preSolution
HideSolutionNode = FALSE
EndGlobalSection
EndGlobal

62
i2c.hpp
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#pragma once
#include <stddef.h>
#include <stdint.h>
#include "hardware.hpp"
namespace i2c {
template <class Driver>
struct I2c {
static void init()
{
Driver::init();
}
template <uint8_t Addr>
static bool start(bool read)
{
return Driver::template start<Addr>(read);
}
static bool write(uint8_t data)
{
return Driver::write(data);
}
template <size_t Bytes>
static bool writeBytes(const uint8_t *buffer)
{
for (size_t i = 0; i < Bytes; ++i) {
if (!write(buffer[i]))
return false;
}
return true;
}
template <bool LastByte = false>
static uint8_t read()
{
return Driver::template read<LastByte>();
}
template <size_t Bytes>
static void readBytes(uint8_t *buffer)
{
static_assert(Bytes > 0, "Must read at least 1 byte");
for (size_t i = 0; i < Bytes - 1; ++i) {
buffer[i] = read();
}
buffer[Bytes - 1] = read<true>();
}
static void stop()
{
Driver::stop();
}
};
} // namespace i2c

4
i2c/clock.hpp Normal file
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#pragma once
#define F_CPU 16000000
#include <util/delay.h>

1
i2c/i2c Submodule

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Subproject commit 5c3fb99c1905559f3a01bf18321b570600a3db2e

196
i2c/i2c.cppproj Normal file
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<?xml version="1.0" encoding="utf-8"?>
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<OutputFileExtension>.elf</OutputFileExtension>
<OutputDirectory>$(MSBuildProjectDirectory)\$(Configuration)</OutputDirectory>
<AssemblyName>i2c</AssemblyName>
<Name>i2c</Name>
<RootNamespace>i2c</RootNamespace>
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<Compile Include="clock.hpp">
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</Compile>
<Compile Include="i2c\i2c.hpp">
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<ItemGroup>
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<Import Project="$(AVRSTUDIO_EXE_PATH)\\Vs\\Compiler.targets" />
</Project>

33
i2c/main.cpp Normal file
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#include "clock.hpp"
#include "i2c/i2c.hpp"
void i2cTest()
{
using namespace i2c;
using config = Hardware<100000>;
I2c<config> twi;
constexpr auto I2CADDRESS = 0x4B;
twi.init();
if (!twi.start<I2CADDRESS>(false)) {
twi.stop();
return;
}
if (!twi.write(0x7F)) {
twi.stop();
return;
}
twi.stop();
}
int main()
{
i2cTest();
return 0;
}