FlashMyPico.com
log in about discover docs scratchpad
This website requires a Chrome-based browser in order to access the WebUSB API. Without it, you may not be able to flash your device.

bme280_spi
for Raspberry Pi Picoโ„ข 2, submitted by flashmypico

Fetching config...

/**
* Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <stdio.h>
#include <string.h>
#include "pico/stdlib.h"
#include "pico/binary_info.h"
#include "hardware/spi.h"
/* Example code to talk to a bme280 humidity/temperature/pressure sensor.
NOTE: Ensure the device is capable of being driven at 3.3v NOT 5v. The Pico
GPIO (and therefore SPI) cannot be used at 5v.
You will need to use a level shifter on the SPI lines if you want to run the
board at 5v.
Connections on Raspberry Pi Pico board and a generic bme280 board, other
boards may vary.
GPIO 16 (pin 21) MISO/spi0_rx-> SDO/SDO on bme280 board
GPIO 17 (pin 22) Chip select -> CSB/!CS on bme280 board
GPIO 18 (pin 24) SCK/spi0_sclk -> SCL/SCK on bme280 board
GPIO 19 (pin 25) MOSI/spi0_tx -> SDA/SDI on bme280 board
3.3v (pin 36) -> VCC on bme280 board
GND (pin 38) -> GND on bme280 board
Note: SPI devices can have a number of different naming schemes for pins. See
the Wikipedia page at https://en.wikipedia.org/wiki/Serial_Peripheral_Interface
for variations.
This code uses a bunch of register definitions, and some compensation code derived
from the Bosch datasheet which can be found here.
https://www.bosch-sensortec.com/media/boschsensortec/downloads/datasheets/bst-bme280-ds002.pdf
*/
#define READ_BIT 0x80
int32_t t_fine;
uint16_t dig_T1;
int16_t dig_T2, dig_T3;
uint16_t dig_P1;
int16_t dig_P2, dig_P3, dig_P4, dig_P5, dig_P6, dig_P7, dig_P8, dig_P9;
uint8_t dig_H1, dig_H3;
int8_t dig_H6;
int16_t dig_H2, dig_H4, dig_H5;
/* The following compensation functions are required to convert from the raw ADC
data from the chip to something usable. Each chip has a different set of
compensation parameters stored on the chip at point of manufacture, which are
read from the chip at startup and used in these routines.
*/
int32_t compensate_temp(int32_t adc_T) {
int32_t var1, var2, T;
var1 = ((((adc_T >> 3) - ((int32_t) dig_T1 << 1))) * ((int32_t) dig_T2)) >> 11;
var2 = (((((adc_T >> 4) - ((int32_t) dig_T1)) * ((adc_T >> 4) - ((int32_t) dig_T1))) >> 12) * ((int32_t) dig_T3))
>> 14;
t_fine = var1 + var2;
T = (t_fine * 5 + 128) >> 8;
return T;
}
uint32_t compensate_pressure(int32_t adc_P) {
int32_t var1, var2;
uint32_t p;
var1 = (((int32_t) t_fine) >> 1) - (int32_t) 64000;
var2 = (((var1 >> 2) * (var1 >> 2)) >> 11) * ((int32_t) dig_P6);
var2 = var2 + ((var1 * ((int32_t) dig_P5)) << 1);
var2 = (var2 >> 2) + (((int32_t) dig_P4) << 16);
var1 = (((dig_P3 * (((var1 >> 2) * (var1 >> 2)) >> 13)) >> 3) + ((((int32_t) dig_P2) * var1) >> 1)) >> 18;
var1 = ((((32768 + var1)) * ((int32_t) dig_P1)) >> 15);
if (var1 == 0)
return 0;
p = (((uint32_t) (((int32_t) 1048576) - adc_P) - (var2 >> 12))) * 3125;
if (p < 0x80000000)
p = (p << 1) / ((uint32_t) var1);
else
p = (p / (uint32_t) var1) * 2;
var1 = (((int32_t) dig_P9) * ((int32_t) (((p >> 3) * (p >> 3)) >> 13))) >> 12;
var2 = (((int32_t) (p >> 2)) * ((int32_t) dig_P8)) >> 13;
p = (uint32_t) ((int32_t) p + ((var1 + var2 + dig_P7) >> 4));
return p;
}
uint32_t compensate_humidity(int32_t adc_H) {
int32_t v_x1_u32r;
v_x1_u32r = (t_fine - ((int32_t) 76800));
v_x1_u32r = (((((adc_H << 14) - (((int32_t) dig_H4) << 20) - (((int32_t) dig_H5) * v_x1_u32r)) +
((int32_t) 16384)) >> 15) * (((((((v_x1_u32r * ((int32_t) dig_H6)) >> 10) * (((v_x1_u32r *
((int32_t) dig_H3))
>> 11) + ((int32_t) 32768))) >> 10) + ((int32_t) 2097152)) *
((int32_t) dig_H2) + 8192) >> 14));
v_x1_u32r = (v_x1_u32r - (((((v_x1_u32r >> 15) * (v_x1_u32r >> 15)) >> 7) * ((int32_t) dig_H1)) >> 4));
v_x1_u32r = (v_x1_u32r < 0 ? 0 : v_x1_u32r);
v_x1_u32r = (v_x1_u32r > 419430400 ? 419430400 : v_x1_u32r);
return (uint32_t) (v_x1_u32r >> 12);
}
#ifdef PICO_DEFAULT_SPI_CSN_PIN
static inline void cs_select() {
asm volatile("nop \n nop \n nop");
gpio_put(PICO_DEFAULT_SPI_CSN_PIN, 0); // Active low
asm volatile("nop \n nop \n nop");
}
static inline void cs_deselect() {
asm volatile("nop \n nop \n nop");
gpio_put(PICO_DEFAULT_SPI_CSN_PIN, 1);
asm volatile("nop \n nop \n nop");
}
#endif
#if defined(spi_default) && defined(PICO_DEFAULT_SPI_CSN_PIN)
static void write_register(uint8_t reg, uint8_t data) {
uint8_t buf[2];
buf[0] = reg & 0x7f; // remove read bit as this is a write
buf[1] = data;
cs_select();
spi_write_blocking(spi_default, buf, 2);
cs_deselect();
sleep_ms(10);
}
static void read_registers(uint8_t reg, uint8_t *buf, uint16_t len) {
// For this particular device, we send the device the register we want to read
// first, then subsequently read from the device. The register is auto incrementing
// so we don't need to keep sending the register we want, just the first.
reg |= READ_BIT;
cs_select();
spi_write_blocking(spi_default, &reg, 1);
sleep_ms(10);
spi_read_blocking(spi_default, 0, buf, len);
cs_deselect();
sleep_ms(10);
}
/* This function reads the manufacturing assigned compensation parameters from the device */
void read_compensation_parameters() {
uint8_t buffer[26];
read_registers(0x88, buffer, 26);
dig_T1 = buffer[0] | (buffer[1] << 8);
dig_T2 = buffer[2] | (buffer[3] << 8);
dig_T3 = buffer[4] | (buffer[5] << 8);
dig_P1 = buffer[6] | (buffer[7] << 8);
dig_P2 = buffer[8] | (buffer[9] << 8);
dig_P3 = buffer[10] | (buffer[11] << 8);
dig_P4 = buffer[12] | (buffer[13] << 8);
dig_P5 = buffer[14] | (buffer[15] << 8);
dig_P6 = buffer[16] | (buffer[17] << 8);
dig_P7 = buffer[18] | (buffer[19] << 8);
dig_P8 = buffer[20] | (buffer[21] << 8);
dig_P9 = buffer[22] | (buffer[23] << 8);
dig_H1 = buffer[25]; // 0xA1
read_registers(0xE1, buffer, 8);
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) {
uint8_t buffer[8];
read_registers(0xF7, buffer, 8);
*pressure = ((uint32_t) buffer[0] << 12) | ((uint32_t) buffer[1] << 4) | (buffer[2] >> 4);
*temperature = ((uint32_t) buffer[3] << 12) | ((uint32_t) buffer[4] << 4) | (buffer[5] >> 4);
*humidity = (uint32_t) buffer[6] << 8 | buffer[7];
}
#endif
int main() {
stdio_init_all();
#if !defined(spi_default) || !defined(PICO_DEFAULT_SPI_SCK_PIN) || !defined(PICO_DEFAULT_SPI_TX_PIN) || !defined(PICO_DEFAULT_SPI_RX_PIN) || !defined(PICO_DEFAULT_SPI_CSN_PIN)
#warning spi/bme280_spi example requires a board with SPI pins
puts("Default SPI pins were not defined");
#else
printf("Hello, bme280! Reading raw data from registers via SPI...\n");
// This example will use SPI0 at 0.5MHz.
spi_init(spi_default, 500 * 1000);
gpio_set_function(PICO_DEFAULT_SPI_RX_PIN, GPIO_FUNC_SPI);
gpio_set_function(PICO_DEFAULT_SPI_SCK_PIN, GPIO_FUNC_SPI);
gpio_set_function(PICO_DEFAULT_SPI_TX_PIN, GPIO_FUNC_SPI);
// Make the SPI pins available to picotool
bi_decl(bi_3pins_with_func(PICO_DEFAULT_SPI_RX_PIN, PICO_DEFAULT_SPI_TX_PIN, PICO_DEFAULT_SPI_SCK_PIN, GPIO_FUNC_SPI));
// Chip select is active-low, so we'll initialise it to a driven-high state
gpio_init(PICO_DEFAULT_SPI_CSN_PIN);
gpio_set_dir(PICO_DEFAULT_SPI_CSN_PIN, GPIO_OUT);
gpio_put(PICO_DEFAULT_SPI_CSN_PIN, 1);
// Make the CS pin available to picotool
bi_decl(bi_1pin_with_name(PICO_DEFAULT_SPI_CSN_PIN, "SPI CS"));
// See if SPI is working - interrograte the device for its I2C ID number, should be 0x60
uint8_t id;
read_registers(0xD0, &id, 1);
printf("Chip ID is 0x%x\n", id);
read_compensation_parameters();
write_register(0xF2, 0x1); // Humidity oversampling register - going for x1
write_register(0xF4, 0x27);// Set rest of oversampling modes and run mode to normal
int32_t humidity, pressure, temperature;
while (1) {
bme280_read_raw(&humidity, &pressure, &temperature);
// These are the raw numbers from the chip, so we need to run through the
// compensations to get human understandable numbers
temperature = compensate_temp(temperature);
pressure = compensate_pressure(pressure);
humidity = compensate_humidity(humidity);
printf("Humidity = %.2f%%\n", humidity / 1024.0);
printf("Pressure = %dPa\n", pressure);
printf("Temp. = %.2fC\n", temperature / 100.0);
sleep_ms(1000);
}
#endif
}
 
ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”ื”
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
This firmware image was imported from the pico-examples repository. 


Copyright 2020 (c) 2020 Raspberry Pi (Trading) Ltd.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following
   disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
   disclaimer in the documentation and/or other materials provided with the distribution.

3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products
   derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Homepage: https://github.com/raspberrypi/pico-examples
Repository: https://github.com/raspberrypi/pico-examples/tree/master/spi/bme280_spi

โ“˜ Tips

detect device ยฉ 2025 flashmypico.com legal ack