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Fix bme280 example #481

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merged 3 commits into from
May 1, 2024
Merged

Fix bme280 example #481

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d5d784b
Fix reading of dig_H5 and dig_H6
peterharperuk Mar 18, 2024
755f5ff
Fix reading of dig_H1
peterharperuk Mar 18, 2024
e3d5df3
Fix order of reading of temp and pressure
peterharperuk Mar 18, 2024
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16 changes: 8 additions & 8 deletions spi/bme280_spi/bme280_spi.c
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Original file line number Diff line number Diff line change
Expand Up @@ -147,7 +147,7 @@ static void read_registers(uint8_t reg, uint8_t *buf, uint16_t len) {
void read_compensation_parameters() {
uint8_t buffer[26];

read_registers(0x88, buffer, 24);
read_registers(0x88, buffer, 26);

dig_T1 = buffer[0] | (buffer[1] << 8);
dig_T2 = buffer[2] | (buffer[3] << 8);
Expand All @@ -163,15 +163,15 @@ void read_compensation_parameters() {
dig_P8 = buffer[20] | (buffer[21] << 8);
dig_P9 = buffer[22] | (buffer[23] << 8);

dig_H1 = buffer[25];
dig_H1 = buffer[25]; // 0xA1

read_registers(0xE1, buffer, 8);

dig_H2 = buffer[0] | (buffer[1] << 8);
dig_H3 = (int8_t) buffer[2];
dig_H4 = buffer[3] << 4 | (buffer[4] & 0xf);
dig_H5 = (buffer[5] >> 4) | (buffer[6] << 4);
dig_H6 = (int8_t) buffer[7];
dig_H2 = buffer[0] | (buffer[1] << 8); // 0xE1 | 0xE2
dig_H3 = (int8_t) buffer[2]; // 0xE3
dig_H4 = buffer[3] << 4 | (buffer[4] & 0xf); // 0xE4 | 0xE5[3:0]
dig_H5 = (buffer[4] >> 4) | (buffer[5] << 4); // 0xE5[7:4] | 0xE6
dig_H6 = (int8_t) buffer[6]; // 0xE7
}

static void bme280_read_raw(int32_t *humidity, int32_t *pressure, int32_t *temperature) {
Expand Down Expand Up @@ -225,8 +225,8 @@ int main() {

// These are the raw numbers from the chip, so we need to run through the
// compensations to get human understandable numbers
pressure = compensate_pressure(pressure);
temperature = compensate_temp(temperature);
pressure = compensate_pressure(pressure);
humidity = compensate_humidity(humidity);

printf("Humidity = %.2f%%\n", humidity / 1024.0);
Expand Down
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