マスターモード専用のＴＷＩライブラリ。Arduino互換クラスのオマケ付き。(笑)
【仕様】
・マルチマスター
・リピーテッドスタート
・７／１０ビットスレーブアドレス
・クロックストレッチ
・任意の通信速度(50KHz～1MHz)
※バスの信号線の状態によっては最悪永久ループしてしまうことがある。それを防ぐには、
[avr8_config.h] #define CONFIG_RTC_USE 1
に設定したうえで、先にRtc::begin()とRtc::run()を実行しRTCを起動しておくこと。タイムアウトの規定値は200ms。
begin()でタイムアウト指定しても良いが最長でも200usなので短すぎるかな。
【サンプルコード (Microchip Studio)】
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#include "avr8_twi.h" #include "avr8_port.h" #define TWI_SDA Port::PA01 /* ATtiny202/402 */ #define TWI_SCL Port::PA02 /* ATtiny202/402 */ #define TWI_SADDR 0x12 Twi twi0(TWI0); int main(void) { sei(); Clock::setup(); uint8_t wbuf[...] = { ... }; uint8_t rbuf[...]; Port::pinMode(TWI_SDA, Port::INPUT_PULLUP); /* Internal Pullup */ Port::pinMode(TWI_SCL, Port::INPUT_PULLUP); /* Internal Pullup */ twi0.begin(100000UL); twi0.write(TWI_SADDR, wbuf, sizeof(wbuf), false); /* false is repeated start */ twi0.read(TWI_SADDR, rbuf, sizeof(rbuf)); return 0; } |
【サンプルコード (Arduino)】
データバッファサイズは、
[avr8_config.h] #define CONFIG_TWI_IOBUF_SIZE 16
に設定する。
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#include "avr8_twi.h" #include "avr8_port.h" #define TWI_SDA Port::PA01 /* ATtiny202/402 */ #define TWI_SCL Port::PA02 /* ATtiny202/402 */ #define TWI_SADDR 0x12 TwoWire Wire(TWI0); void setup(void) { Port::pinMode(TWI_SDA, Port::INPUT_PULLUP); /* Internal Pullup */ Port::pinMode(TWI_SCL, Port::INPUT_PULLUP); /* Internal Pullup */ Wire.begin(100000UL); } void loop(void) { Wire.beginTransmission(TWI_SADDR); Wire.write(...); Wire.endTransmission(false); /* false is repeated start */ Wire.requestFrom(TWI_SADDR, ...); if (Wire.available()) { Wire.read(...); ... } } |
【ライブラリ】
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/* avr8_twi.h - TWI Driver for Microchip AVR8 Series Copyright (c) 2025 Sasapea's Lab. All right reserved. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or at your option) any later version. This program 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 General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <https://www.gnu.org/licenses/>. */ #pragma once #include "avr8_config.h" #include "avr8_clock.h" #if CONFIG_RTC_USE #include "avr8_rtc.h" #endif #if defined(TWI1) #define TWI_MAX_CH 2 #elif defined(TWI0) #define TWI_MAX_CH 1 #else #define TWI_MAX_CH 0 #endif #if !defined(CONFIG_TWI_BUS_TIMEOUT) #define CONFIG_TWI_BUS_TIMEOUT 200000 #endif class Twi { public: /* SDA Setup Time select */ typedef enum { SDASETUP_4CYC = TWI_SDASETUP_4CYC_gc, /* SDA setup time is 4 clock cycles */ SDASETUP_8CYC = TWI_SDASETUP_8CYC_gc, /* SDA setup time is 8 clock cycles */ } SDASETUP; /* SDA Hold Time select */ typedef enum { SDAHOLD_OFF = TWI_SDAHOLD_OFF_gc, /* SDA hold time off */ SDAHOLD_50NS = TWI_SDAHOLD_50NS_gc, /* Typical 50ns hold time */ SDAHOLD_300NS = TWI_SDAHOLD_300NS_gc, /* Typical 300ns hold time */ SDAHOLD_500NS = TWI_SDAHOLD_500NS_gc, /* Typical 500ns hold time */ } SDAHOLD; /* Inactive Bus Timeout select */ typedef enum { TIMEOUT_DISABLED = TWI_TIMEOUT_DISABLED_gc, /* Bus Timeout Disabled */ TIMEOUT_50US = TWI_TIMEOUT_50US_gc, /* 50 Microseconds */ TIMEOUT_100US = TWI_TIMEOUT_100US_gc, /* 100 Microseconds */ TIMEOUT_200US = TWI_TIMEOUT_200US_gc, /* 200 Microseconds */ } TIMEOUT; /* Error Code */ typedef enum { ERROR_NO_SLAVE = -1, ERROR_TRANSFER = -2, } ERROR; Twi(TWI_t& twi, SDAHOLD hold = SDAHOLD_OFF, SDASETUP setup = SDASETUP_4CYC) : _twi(&twi), _ch((&twi - &TWI0) / sizeof(twi)) { _instances[_ch] = this; twi.CTRLA = setup | hold; twi.DBGCTRL = 0; } /* virtual */ ~Twi(void) { end(); _instances[_ch] = 0; } void begin(uint32_t speed = 100000UL, TIMEOUT timeout = TIMEOUT_DISABLED) { end(); _twi->CTRLA = (_twi->CTRLA & ~TWI_FMPEN_bm) | (speed >= 700000UL ? TWI_FMPEN_bm : 0); uint16_t baud = Clock::frequency() / speed / 2; _twi->MBAUD = baud <= 7 ? 1 : (baud > 0xFF + 7 ? 0xFF : baud - 7); _twi->MSTATUS = ~TWI_BUSSTATE_gm | TWI_BUSSTATE_IDLE_gc; _twi->MCTRLB = 0; _twi->MCTRLA = timeout | TWI_ENABLE_bm; } void end(void) { _twi->MCTRLA = 0; } void dbgctrl(bool dbgrun = true) { _twi->DBGCTRL = dbgrun; } int write(uint16_t addr, const void* buf, uint8_t len, bool stop = true) { int cnt = ERROR_NO_SLAVE; STATE state = start(addr, 0); if (state == STATE_ERROR) cnt = ERROR_TRANSFER; else if (state == STATE_ACK) { const uint8_t* p = (const uint8_t*)buf; for (cnt = 0; cnt < len; ++cnt) { _twi->MDATA = *p++; STATE state = wait(); if (state == STATE_NAK) break; if (state == STATE_ERROR) { cnt = ERROR_TRANSFER; break; } } cmd(stop || (state != STATE_ACK) ? CMD_STOP : CMD_REPSTART); } return cnt; } int read(uint16_t addr, void* buf, uint8_t len, bool stop = true) { int cnt = ERROR_NO_SLAVE; STATE state = start(addr, 1); if (state == STATE_ERROR) cnt = ERROR_TRANSFER; else if (state == STATE_ACK) { uint8_t* p = (uint8_t*)buf; for (cnt = 0; cnt < len; ++cnt) { if (cnt) cmd(CMD_RECVTRANS); STATE state = wait(); if (state == STATE_ERROR) { cnt = ERROR_TRANSFER; break; } *p++ = _twi->MDATA; } cmd(stop || (state == STATE_ERROR) ? CMD_STOP : CMD_REPSTART, ACKACT_NACK); } return cnt; } protected: /* Acknowledge Action select */ typedef enum { ACKACT_ACK = TWI_ACKACT_ACK_gc, /* Send ACK */ ACKACT_NACK = TWI_ACKACT_NACK_gc, /* Send NACK */ } ACKACT; /* Command select */ typedef enum { CMD_NOACT = TWI_MCMD_NOACT_gc, /* No Action */ CMD_REPSTART = TWI_MCMD_REPSTART_gc, /* Issue Repeated Start Condition */ CMD_RECVTRANS = TWI_MCMD_RECVTRANS_gc, /* Receive or Transmit Data, depending on DIR */ CMD_STOP = TWI_MCMD_STOP_gc, /* Issue Stop Condition */ } CMD; typedef enum { STATE_ACK, STATE_NAK, STATE_ERROR, } STATE; static Twi* _instances[TWI_MAX_CH]; TWI_t* _twi; uint8_t _ch; void cmd(CMD cmd, ACKACT ack = ACKACT_ACK) { _twi->MCTRLB = (_twi->MCTRLB & ~(TWI_ACKACT_bm | TWI_MCMD_gm)) | cmd | ack; } STATE start(uint16_t addr, bool read) { STATE state; if (addr & ~0x03FF) return STATE_NAK; cmd(CMD_NOACT); if (addr <= 0x7F) { _twi->MADDR = (addr << 1) | read; // write or read mode state = wait(); } else { _twi->MADDR = 0xF0 | ((addr >> 8) << 1) | 0; // write mode state = wait(); if (state == STATE_ACK) { _twi->MDATA = (uint8_t)addr; state = wait(); if ((state == STATE_ACK) && read) { cmd(CMD_REPSTART); _twi->MADDR |= 1; // read mode state = wait(); } } } if (state != STATE_ACK) cmd(CMD_STOP); return state; } STATE wait(void) { #if CONFIG_RTC_USE uint32_t t = Rtc::read(); while (Rtc::read() - t < RTC_US2TICK(CONFIG_TWI_BUS_TIMEOUT)) #else while (1) #endif { uint8_t status = _twi->MSTATUS; if (status & (TWI_BUSERR_bm | TWI_ARBLOST_bm)) break; if (status & (TWI_WIF_bm | TWI_RIF_bm)) return status & TWI_RXACK_bm ? STATE_NAK : STATE_ACK; avr8_yield(); } return STATE_ERROR; } }; /* Arduino compatible class */ class TwoWire : Twi { public: TwoWire(TWI_t& twi, SDAHOLD hold = SDAHOLD_OFF, SDASETUP setup = SDASETUP_4CYC) : Twi(twi, hold, setup), _addr(0), _error(0), _count(0), _index(0) { } void begin(uint32_t speed = 100000UL, TIMEOUT timeout = TIMEOUT_DISABLED) { Twi::begin(speed, timeout); } void end(void) { Twi::end(); } void beginTransmission(uint16_t address) { _addr = address; _count = 0; _index = 0; _error = 0; } size_t write(uint8_t data) { if (_index >= sizeof(_buffer)) { _error = 1; return 0; } _buffer[_index++] = data; return 1; } size_t write(const void *buf, size_t len) { uint8_t cnt = 0; const uint8_t *p = (const uint8_t *)buf; while (len--) cnt += write(*p++); return cnt; } int endTransmission(bool sendStop = true) { if (_error) return 1; // buffer overflow int len = Twi::write(_addr, _buffer, _index, sendStop); return len == (int)_index ? 0 : (len < 0 ? 2 : 3); } int requestFrom(uint16_t address, size_t quantity, bool sendStop = true) { if (quantity > sizeof(_buffer)) quantity = sizeof(_buffer); int len = Twi::read(address, _buffer, quantity, sendStop); _index = 0; return _count = len > 0 ? len : 0; } size_t available(void) { return _index < _count ? _count - _index : 0; } int read(void) { return _index < _count ? _buffer[_index++] : -1; } size_t readBytes(void *buf, size_t len) { size_t cnt = 0; uint8_t* p = (uint8_t*)buf; for (; cnt < len; ++cnt) { int c = read(); if (c < 0) break; *p++ = c; } return cnt; } int peek(void) { return _index < _count ? _buffer[_index] : -1; } private: uint16_t _addr; int _error; size_t _count; size_t _index; uint8_t _buffer[CONFIG_TWI_IOBUF_SIZE]; }; |
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/* avr8_twi.cpp - TWI Driver for Microchip AVR8 Series Copyright (c) 2025 Sasapea's Lab. All right reserved. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or at your option) any later version. This program 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 General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <https://www.gnu.org/licenses/>. */ #include "avr8_twi.h" Twi* Twi::_instances[]; |
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