diff options
Diffstat (limited to 'tests/i2c-master')
| -rw-r--r-- | tests/i2c-master/i2c-master.c | 40 |
1 files changed, 23 insertions, 17 deletions
diff --git a/tests/i2c-master/i2c-master.c b/tests/i2c-master/i2c-master.c index a1e0fa7..92b0b77 100644 --- a/tests/i2c-master/i2c-master.c +++ b/tests/i2c-master/i2c-master.c @@ -25,29 +25,35 @@ enum sht21_cmd_e { /* 0xfa, 0x0f to read serial */ }; +/* requires clock to be a multiple of 2 ! */ +// TODO - plausible to pull up to library, with extraction of 100k param too? +static void i2c_set_speed_100k(uint32_t p, uint32_t clock_megahz) +{ +#if defined I2C_SR2 + /* target 2Mhz input, so tpresc = 500ns */ + int prescaler = clock_megahz / 2 - 1; + i2c_set_prescaler(p, prescaler); + i2c_set_scl_low_period(p, 9); // 5usecs + i2c_set_scl_high_period(p, 7); // 4usecs + i2c_set_data_hold_time(p, 1); // 0.5usecs + i2c_set_data_setup_time(p, 2); // 1.25usecs +#else + i2c_set_clock_frequency(p, clock_megahz); + i2c_set_standard_mode(p); + /* x Mhz / (100kHz * 2) */ + i2c_set_ccr(p, clock_megahz * 5); + /* Sm mode, (100kHz) freqMhz + 1 */ + i2c_set_trise(p, clock_megahz + 1); +#endif +} + void i2cm_init(void) { rcc_periph_clock_enable(hw_details.periph_rcc); rcc_periph_reset_pulse(hw_details.periph_rst); // i2c_enable_ack(hw_details.periph); /* NO ACK FOR SHT21! */ - //i2c_set_dutycycle(hw_details.periph, I2C_CCR_DUTY_DIV2); /* default, no need to do this really */ -#if defined I2C_SR2 - i2c_set_clock_frequency(hw_details.periph, hw_details.i2c_clock_megahz); - i2c_set_standard_mode(hw_details.periph); - /* x Mhz / (100kHz * 2) */ - i2c_set_ccr(hw_details.periph, hw_details.i2c_clock_megahz * 5); - /* Sm mode, (100kHz) freqMhz + 1 */ - i2c_set_trise(hw_details.periph, hw_details.i2c_clock_megahz + 1); -#else - // V2 periph - // See Table 85. Examples of timings settings for f I2CCLK = 48 MHz - i2c_set_prescaler(hw_details.periph, 0xb); // 11 +1 = 2, so 4Mhz input - i2c_set_scl_low_period(hw_details.periph, 0x13); - i2c_set_scl_high_period(hw_details.periph, 0xF); - i2c_set_data_hold_time(hw_details.periph, 0x2); - i2c_set_data_setup_time(hw_details.periph, 0x4); -#endif + i2c_set_speed_100k(hw_details.periph, hw_details.i2c_clock_megahz); i2c_peripheral_enable(hw_details.periph); } |