127 lines
1.9 KiB
C++
127 lines
1.9 KiB
C++
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#include "soft_twi.hpp"
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#include <Arduino.h>
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SoftTWI::SoftTWI(unsigned pin_sda, unsigned pin_scl, unsigned delay) {
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_pin_scl = pin_scl;
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_pin_sda = pin_sda;
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_delay = delay;
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}
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void SoftTWI::begin() {
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digitalWrite(_pin_sda, 0);
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digitalWrite(_pin_scl, 0);
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}
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void SoftTWI::sleep(unsigned t) {
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if(_delay) {
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delayMicroseconds(_delay * t);
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}
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}
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void SoftTWI::set_sda(bool s) {
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pinMode(_pin_sda, s ? INPUT : OUTPUT);
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}
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void SoftTWI::set_scl(bool s) {
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pinMode(_pin_scl, s ? INPUT : OUTPUT);
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}
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bool SoftTWI::read_sda() {
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return digitalRead(_pin_sda);
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}
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bool SoftTWI::read_scl() {
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return digitalRead(_pin_scl);
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}
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void SoftTWI::wait_scl() {
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while(!read_scl()) {}
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}
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bool SoftTWI::read_bit() {
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set_sda(1);
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sleep();
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set_scl(1);
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sleep(2);
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wait_scl();
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bool s = read_sda();
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set_scl(0);
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sleep();
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return s;
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}
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void SoftTWI::write_bit(bool s) {
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set_sda(s);
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sleep();
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set_scl(1);
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sleep(2);
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wait_scl();
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set_scl(0);
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sleep();
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}
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void SoftTWI::start() {
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set_sda(1);
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sleep();
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set_scl(1);
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sleep();
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set_sda(0);
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sleep();
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set_scl(0);
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sleep();
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}
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void SoftTWI::end() {
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set_sda(0);
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sleep();
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set_scl(1);
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sleep();
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set_sda(1);
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sleep(2);
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}
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bool SoftTWI::start_read(uint8_t addr) {
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start();
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return write((addr << 1) | 1);
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}
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bool SoftTWI::start_write(uint8_t addr) {
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start();
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return write(addr << 1);
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}
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uint8_t SoftTWI::read(bool ack) {
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uint8_t v = 0;
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for(unsigned m = 0x80; m; m >>= 1) {
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if(read_bit()) {
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v |= m;
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}
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}
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write_bit(!ack); // send ACK
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return v;
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}
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bool SoftTWI::write(uint8_t v) {
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for(unsigned m = 0x80; m; m >>= 1) {
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write_bit(v & m);
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}
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return !read_bit(); // get ACK
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}
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unsigned SoftTWI::write(const uint8_t* data, unsigned data_len) {
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for(unsigned i = 0; i < data_len; i++) {
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if(!write(data[i])) {
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return i;
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}
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}
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return data_len;
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}
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void SoftTWI::read(uint8_t* data, unsigned data_len, bool nack_at_end) {
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for(unsigned i = 0; i < data_len; i++) {
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data[i] = read(nack_at_end ? (i < data_len - 1) : true);
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}
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}
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