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-rw-r--r--tests/i2c-master/i2c-master.c40
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);
}