diff options
Diffstat (limited to 'src/driver')
| -rw-r--r-- | src/driver/soft_i2c.cc | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/src/driver/soft_i2c.cc b/src/driver/soft_i2c.cc index 33f77ab..99a88aa 100644 --- a/src/driver/soft_i2c.cc +++ b/src/driver/soft_i2c.cc @@ -2,6 +2,13 @@ #include "driver/gpio.h" #include "arch.h" +#ifdef SOFTI2C_TIMER +#ifdef TIMER_CYCLES +#error "SOFTI2C_TIMER and TIMER_CYCLES are mutually exclusive" +#endif +#include "driver/timer.h" +#endif + #ifdef SOFTI2C_PULLUP #define SDA_HIGH gpio.input(sda, 1) #define SDA_LOW gpio.output(sda, 0) @@ -14,6 +21,8 @@ #define SCL_LOW gpio.output(scl) #endif +#ifndef SOFTI2C_TIMER + signed char SoftI2C::setup() { SDA_HIGH; @@ -136,6 +145,159 @@ signed char SoftI2C::xmit(unsigned char address, return 0; } +#else + +#ifndef F_I2C +#define F_I2C 100000 +#endif + +volatile unsigned char timer_done = 0; + +inline void await_timer() +{ + timer_done = 0; + timer.start(1); + while (!timer_done) { + arch.idle(); + } + timer.stop(); +} + +signed char SoftI2C::setup() +{ + SDA_HIGH; + SCL_HIGH; + /* + * I2C frequency is the time between two SCL low->high transitions + * (or high->low, whatever you prefer). For the timer, we need to set the + * time between SCL low->high and the following high->low transition + * (and vice versa), which is twice the desired I2C frequency. Also, + * timer.setup wants kHz and not Hz, so we have + * Timer Freq [kHz] = I2C Freq [Hz] * 2 / 1000 + */ + timer.setup(F_I2C / 500); + return 0; +} + +void SoftI2C::start() +{ + SDA_HIGH; + SCL_HIGH; + await_timer(); + SDA_LOW; + await_timer(); + SCL_LOW; + await_timer(); +} + +void SoftI2C::stop() +{ + SCL_LOW; + SDA_LOW; + await_timer(); + SCL_HIGH; + await_timer(); + SDA_HIGH; +} + +bool SoftI2C::tx(unsigned char byte) +{ + unsigned char got_ack = 0; + for (unsigned char i = 0; i <= 8; i++) { + if ((byte & 0x80) || (i == 8)) { + SDA_HIGH; + } else { + SDA_LOW; + } + byte <<= 1; + SCL_HIGH; + await_timer(); + while (!gpio.read(scl)) ; + if (i == 8) { + if (!gpio.read(sda)) { + got_ack = 1; + } + } + SCL_LOW; + await_timer(); + } + return got_ack; +} + +unsigned char SoftI2C::rx(bool send_ack) +{ + unsigned char byte = 0; + SDA_HIGH; + for (unsigned char i = 0; i <= 8; i++) { + SCL_HIGH; + await_timer(); + while (!gpio.read(scl)) ; + if ((i < 8) && gpio.read(sda)) { + byte |= 1 << (7 - i); + } + SCL_LOW; + await_timer(); + if ((i == 7) && send_ack) { + SDA_LOW; + } else if ((i == 8) && send_ack) { + SDA_HIGH; + } + } + return byte; +} + +void SoftI2C::scan(unsigned int *results) +{ + unsigned char i2caddr; + for (unsigned char address = 0; address < 128; address++) { + + i2caddr = (address << 1) | 0; + + start(); + + if (tx(i2caddr)) { + results[address / (8 * sizeof(unsigned int))] |= 1 << (address % (8 * sizeof(unsigned int))); + stop(); + } + } + stop(); +} + +signed char SoftI2C::xmit(unsigned char address, + unsigned char tx_len, unsigned char *tx_buf, + unsigned char rx_len, unsigned char *rx_buf) +{ + unsigned char i; + + if (tx_len) { + start(); + tx((address << 1) | 0); + + for (i = 0; i < tx_len; i++) { + tx(tx_buf[i]); + } + } + if (rx_len) { + start(); + tx((address << 1) | 1); + + for (i = 1; i <= rx_len; i++) { + rx_buf[i-1] = rx((i < rx_len) * 1); + } + } + + stop(); + + return 0; +} + +ON_TIMER_INTERRUPT +{ + timer_done = 1; +} + +#endif + #ifdef MULTIPASS_ARCH_esp8266 SoftI2C i2c(GPIO::d7, GPIO::d8); #elif MULTIPASS_ARCH_arduino_nano |