bmp280: read out via DMA in the background
This removes any busy waiting on the I²C from the main loop. Initialization is still done in a blocking way.
This commit is contained in:
parent
055186180f
commit
07dd91ecc2
178
src/bmp280.c
178
src/bmp280.c
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@ -1,6 +1,8 @@
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#include <libopencm3/stm32/i2c.h>
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#include <libopencm3/stm32/gpio.h>
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#include "i2c_dma.h"
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#include "pinout.h"
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#include "bmp280_comp.h"
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@ -8,6 +10,17 @@
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#define BMP280_7BIT_ADDR 0x76
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typedef enum {
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READY,
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SEND_REQUEST,
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WAIT_MEASUREMENT_COMPLETE,
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READ_RESULTS,
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COMPENSATE_TEMPERATURE,
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COMPENSATE_PRESSURE
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} bmp280_readout_state_t;
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static bmp280_readout_state_t m_readout_state;
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// calibration value cache, shared with bmp280_comp.c
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extern uint16_t dig_T1;
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@ -27,6 +40,13 @@ extern int16_t dig_P9;
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static fxp_t m_last_temperature = 0;
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static fxp_t m_last_pressure = 0;
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static int32_t m_temp_raw;
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static int32_t m_press_raw;
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static void cb_i2c_dma(const uint8_t *rdata, size_t rlen);
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bool bmp280_init(void)
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{
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// configure pins for I2C1
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@ -95,6 +115,8 @@ bool bmp280_init(void)
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dig_P8 = (((int16_t)(int8_t)rdata[21]) << 8) | rdata[20]; // 0x9C, 0x9D
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dig_P9 = (((int16_t)(int8_t)rdata[23]) << 8) | rdata[22]; // 0x9E, 0x9F
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i2c_dma_init(cb_i2c_dma);
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return true;
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err_out:
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@ -102,63 +124,123 @@ err_out:
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}
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static void trigger_read_status_register(void)
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{
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uint8_t wdata[1];
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uint8_t wsize = 0, rsize;
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wdata[wsize++] = 0xF3; // status register
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rsize = 1;
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i2c_dma_start_transfer7(I2C1, BMP280_7BIT_ADDR, wdata, wsize, rsize);
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}
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static void trigger_read_results(void)
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{
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uint8_t wdata[1];
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uint8_t wsize = 0, rsize;
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wdata[wsize++] = 0xF7;
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rsize = 8;
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i2c_dma_start_transfer7(I2C1, BMP280_7BIT_ADDR, wdata, wsize, rsize);
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}
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static void cb_i2c_dma(const uint8_t *rdata, size_t rlen)
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{
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(void)rlen;
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switch(m_readout_state) {
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case SEND_REQUEST:
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m_readout_state = WAIT_MEASUREMENT_COMPLETE;
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trigger_read_status_register();
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break;
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case WAIT_MEASUREMENT_COMPLETE:
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if((rdata[0] & 0x09) != 0) {
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// either "measuring" or "im_update" is active, so measurement is not complete yet.
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// try again:
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trigger_read_status_register();
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} else {
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m_readout_state = READ_RESULTS;
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trigger_read_results();
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}
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break;
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case READ_RESULTS:
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m_press_raw =
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((int32_t)rdata[0] << 12) // press_msb (0xF7)
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| ((int32_t)rdata[1] << 4) // press_lsb (0xF8)
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| ((int32_t)rdata[2] >> 4); // press_xlsb (0xF9)
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m_temp_raw =
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((int32_t)rdata[3] << 12) // temp_msb (0xFA)
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| ((int32_t)rdata[4] << 4) // temp_lsb (0xFB)
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| ((int32_t)rdata[5] >> 4); // temp_xlsb (0xFC)
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m_readout_state = COMPENSATE_TEMPERATURE;
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break;
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default:
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// should never happen
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while(1);
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break;
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}
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}
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bool bmp280_loop(void)
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{
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bool retval = false;
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switch(m_readout_state) {
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case READY:
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// nothing to do in this state
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break;
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case SEND_REQUEST:
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case WAIT_MEASUREMENT_COMPLETE:
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case READ_RESULTS:
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// handled in cb_i2c_dma exclusively
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break;
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case COMPENSATE_TEMPERATURE:
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m_last_temperature = bmp280_comp_temperature(m_temp_raw);
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m_readout_state = COMPENSATE_PRESSURE;
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break;
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case COMPENSATE_PRESSURE:
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m_last_pressure = bmp280_comp_pressure(m_press_raw);
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m_readout_state = READY;
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retval = true;
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break;
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}
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if(m_readout_state != READY) {
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i2c_dma_loop();
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}
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return retval;
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}
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bool bmp280_start_measurement(void)
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{
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uint8_t wdata[2];
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uint8_t wsize = 0;
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if(m_readout_state != READY) {
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return false; // still busy
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}
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wdata[wsize++] = 0xF4; // measurement control register
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wdata[wsize++] = (0x01 << 5) | (0x01 << 2) | 0x01; // pressure x1, temp x1, forced mode
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i2c_transfer7(I2C1, BMP280_7BIT_ADDR, wdata, wsize, NULL, 0);
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i2c_dma_start_transfer7(I2C1, BMP280_7BIT_ADDR, wdata, wsize, 0);
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return true;
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}
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bool bmp280_is_measurement_complete(void)
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{
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uint8_t wdata[1];
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uint8_t rdata[1];
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uint8_t wsize = 0, rsize;
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wdata[wsize++] = 0xF3; // status register
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rsize = 1;
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i2c_transfer7(I2C1, BMP280_7BIT_ADDR, wdata, wsize, rdata, rsize);
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if((rdata[0] & 0x09) != 0) {
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// either "measuring" or "im_update" is active, so measurement is not complete yet.
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return false;
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} else {
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return true;
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}
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}
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bool bmp280_readout_and_compensate(void)
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{
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uint8_t wdata[1];
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uint8_t rdata[8];
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uint8_t wsize = 0, rsize;
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wdata[wsize++] = 0xF7;
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rsize = 8;
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i2c_transfer7(I2C1, BMP280_7BIT_ADDR, wdata, wsize, rdata, rsize);
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int32_t press_raw =
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((int32_t)rdata[0] << 12) // press_msb (0xF7)
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| ((int32_t)rdata[1] << 4) // press_lsb (0xF8)
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| ((int32_t)rdata[2] >> 4); // press_xlsb (0xF9)
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int32_t temp_raw =
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((int32_t)rdata[3] << 12) // temp_msb (0xFA)
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| ((int32_t)rdata[4] << 4) // temp_lsb (0xFB)
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| ((int32_t)rdata[5] >> 4); // temp_xlsb (0xFC)
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m_last_temperature = bmp280_comp_temperature(temp_raw);
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m_last_pressure = bmp280_comp_pressure(press_raw);
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m_readout_state = SEND_REQUEST;
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return true;
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}
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@ -7,10 +7,9 @@
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#include <fxp.h>
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bool bmp280_init(void);
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bool bmp280_loop(void); // returns true if measurements have been updated
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bool bmp280_start_measurement(void);
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bool bmp280_is_measurement_complete(void);
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bool bmp280_readout_and_compensate(void);
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fxp_t bmp280_get_temperature(void);
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fxp_t bmp280_get_pressure(void);
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@ -0,0 +1,148 @@
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#include <string.h>
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#include <libopencm3/stm32/i2c.h>
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#include <libopencm3/stm32/dma.h>
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#include "i2c_dma.h"
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#include "rs485.h"
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#define DMA_CHANNEL_TX DMA_CHANNEL2
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#define DMA_CHANNEL_RX DMA_CHANNEL3
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static uint8_t m_wdata[2];
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static uint8_t m_wlen;
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static uint8_t m_rdata[32];
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static uint8_t m_rlen;
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static uint8_t m_addr;
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static uint32_t m_i2c;
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typedef enum {
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IDLE,
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SEND_DATA,
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RECEIVE_DATA
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} i2c_dma_state_t;
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static i2c_dma_state_t m_state;
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static i2c_dma_callback_t m_callback;
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static void setup_txdma(void)
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{
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dma_channel_reset(DMA1, DMA_CHANNEL_TX);
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dma_set_priority(DMA1, DMA_CHANNEL_TX, DMA_CCR_PL_LOW);
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dma_set_memory_size(DMA1, DMA_CHANNEL_TX, DMA_CCR_MSIZE_8BIT);
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dma_set_peripheral_size(DMA1, DMA_CHANNEL_TX, DMA_CCR_PSIZE_8BIT);
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dma_enable_memory_increment_mode(DMA1, DMA_CHANNEL_TX);
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dma_set_read_from_memory(DMA1, DMA_CHANNEL_TX);
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dma_set_peripheral_address(DMA1, DMA_CHANNEL_TX, (uint32_t) &I2C_TXDR(m_i2c));
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// send m_wlen bytes from m_wdata
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dma_set_memory_address(DMA1, DMA_CHANNEL_TX, (uint32_t)m_wdata);
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dma_set_number_of_data(DMA1, DMA_CHANNEL_TX, m_wlen);
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dma_enable_channel(DMA1, DMA_CHANNEL_TX);
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i2c_enable_txdma(m_i2c);
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}
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static void setup_rxdma(void)
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{
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dma_channel_reset(DMA1, DMA_CHANNEL_RX);
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dma_set_priority(DMA1, DMA_CHANNEL_RX, DMA_CCR_PL_LOW);
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dma_set_memory_size(DMA1, DMA_CHANNEL_RX, DMA_CCR_MSIZE_8BIT);
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dma_set_peripheral_size(DMA1, DMA_CHANNEL_RX, DMA_CCR_PSIZE_8BIT);
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dma_enable_memory_increment_mode(DMA1, DMA_CHANNEL_RX);
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dma_set_read_from_peripheral(DMA1, DMA_CHANNEL_RX);
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dma_set_peripheral_address(DMA1, DMA_CHANNEL_RX, (uint32_t) &I2C_RXDR(m_i2c));
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// receive m_rlen bytes and store them in m_rdata
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dma_set_memory_address(DMA1, DMA_CHANNEL_RX, (uint32_t)m_rdata);
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dma_set_number_of_data(DMA1, DMA_CHANNEL_RX, m_rlen);
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dma_enable_channel(DMA1, DMA_CHANNEL_RX);
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i2c_enable_rxdma(m_i2c);
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}
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void i2c_dma_init(i2c_dma_callback_t callback)
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{
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m_callback = callback;
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m_state = IDLE;
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}
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void i2c_dma_loop(void)
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{
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switch(m_state) {
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case IDLE:
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// nothing to do
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return;
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case SEND_DATA:
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//if(i2c_transfer_complete(m_i2c)) { // does not work for some reason :(
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if(dma_get_interrupt_flag(DMA1, DMA_CHANNEL_TX, DMA_TCIF)) {
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dma_clear_interrupt_flags(DMA1, DMA_CHANNEL_TX, DMA_TCIF);
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if(m_rlen) {
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m_state = RECEIVE_DATA;
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i2c_set_7bit_address(m_i2c, m_addr);
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i2c_set_read_transfer_dir(m_i2c);
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i2c_set_bytes_to_transfer(m_i2c, m_rlen);
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i2c_send_start(m_i2c);
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i2c_enable_autoend(m_i2c); // important to do it after start() for a proper repeated start!
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setup_rxdma();
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} else {
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// no RX requested => we are done here
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m_state = IDLE;
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m_callback(NULL, 0);
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}
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}
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break;
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case RECEIVE_DATA:
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//if(i2c_transfer_complete(m_i2c)) { // does not work for some reason :(
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if(dma_get_interrupt_flag(DMA1, DMA_CHANNEL_RX, DMA_TCIF)) {
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dma_clear_interrupt_flags(DMA1, DMA_CHANNEL_RX, DMA_TCIF);
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m_state = IDLE;
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m_callback(m_rdata, m_rlen);
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}
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break;
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}
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}
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void i2c_dma_start_transfer7(uint32_t i2c, uint8_t addr, const uint8_t *w, size_t wn, size_t rn)
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{
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m_wlen = wn;
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m_rlen = rn;
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memcpy(m_wdata, w, wn);
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m_state = SEND_DATA;
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m_i2c = i2c;
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m_addr = addr;
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i2c_set_7bit_address(i2c, addr);
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i2c_set_write_transfer_dir(i2c);
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i2c_set_bytes_to_transfer(i2c, wn);
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if(rn) {
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i2c_disable_autoend(i2c); // prepare repeated start
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} else {
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i2c_enable_autoend(i2c); // stop condition after write transfer
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}
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i2c_send_start(i2c); // start the transfer. The rest is handled by the DMA.
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setup_txdma();
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}
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@ -0,0 +1,21 @@
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#ifndef I2C_DMA_H
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#define I2C_DMA_H
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#include <stdint.h>
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#include <stddef.h>
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typedef enum
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{
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I2C_DMA_EVT_TRANSFER_COMPLETE,
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I2C_DMA_EVT_ADDR_NAK,
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} i2c_dma_evt_t;
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typedef void (*i2c_dma_callback_t)(const uint8_t *rdata, size_t rlen);
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void i2c_dma_init(i2c_dma_callback_t callback);
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void i2c_dma_loop(void);
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void i2c_dma_start_transfer7(uint32_t i2c, uint8_t addr, const uint8_t *w, size_t wn, size_t rn);
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#endif // I2C_DMA_H
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10
src/main.c
10
src/main.c
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@ -27,7 +27,6 @@ static enum {
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BMP280_NOT_PRESENT,
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BMP280_IDLE,
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BMP280_MEASURING,
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BMP280_READOUT
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} bmp280_state;
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/* Set up systick to fire freq times per second */
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@ -280,15 +279,10 @@ static void handle_bmp280(uint64_t timebase_ms)
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break;
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case BMP280_MEASURING:
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if(timebase_ms % 10 == 0 && bmp280_is_measurement_complete()) {
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bmp280_state = BMP280_READOUT;
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if(timebase_ms % 10 == 0 && bmp280_loop()) {
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bmp280_state = BMP280_IDLE;
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}
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break;
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case BMP280_READOUT:
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bmp280_readout_and_compensate();
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bmp280_state = BMP280_IDLE;
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break;
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}
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}
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