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twi safe init

This commit is contained in:
Alex Voinea 2022-02-25 19:36:55 +01:00 committed by D.R.racer
parent 28c527fece
commit abbf2a3927
2 changed files with 19 additions and 2 deletions
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2
Firmware/swi2c.c
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@ -30,7 +30,7 @@ void swi2c_init(void)
SET_INPUT(SWI2C_SDA); SET_INPUT(SWI2C_SDA);
WRITE(SWI2C_SDA, 1); //SDA must be input with pullups while we are not sure if the slave is outputing or not WRITE(SWI2C_SDA, 1); //SDA must be input with pullups while we are not sure if the slave is outputing or not
WRITE(SWI2C_SCL, 1); WRITE(SWI2C_SCL, 0);
SET_OUTPUT(SWI2C_SCL); //SCL can be an output at all times. The bus is not in a multi-master configuration. SET_OUTPUT(SWI2C_SCL); //SCL can be an output at all times. The bus is not in a multi-master configuration.
for (uint8_t i = 0; i < 100; i++) //wait. Not sure what for, but wait anyway. for (uint8_t i = 0; i < 100; i++) //wait. Not sure what for, but wait anyway.

19
Firmware/twi.cpp
View File

@ -21,6 +21,7 @@
#include <math.h> #include <math.h>
#include <util/delay.h>
#include "config.h" #include "config.h"
#include "fastio.h" #include "fastio.h"
#include "twi.h" #include "twi.h"
@ -29,8 +30,24 @@
void twi_init(void) void twi_init(void)
{ {
// activate internal pullups for twi. // activate internal pullups for SDA
SET_INPUT(SDA_PIN);
WRITE(SDA_PIN, 1); WRITE(SDA_PIN, 1);
// start with the SDA pulled low
WRITE(SCL_PIN, 0);
SET_OUTPUT(SCL_PIN);
// clock 10 cycles to make sure that the sensor is not stuck in a register read.
for (uint8_t i = 0; i < 10; i++) {
WRITE(SCL_PIN, 1);
_delay_us((1000000 / TWI_FREQ) / 2);
WRITE(SCL_PIN, 0);
_delay_us((1000000 / TWI_FREQ) / 2);
}
// activate internal pullups for SCL
SET_INPUT(SCL_PIN);
WRITE(SCL_PIN, 1); WRITE(SCL_PIN, 1);
// initialize twi prescaler and bit rate // initialize twi prescaler and bit rate