ESP32-CAM not reading BME680

Question

I am trying to read BME680 on ESP32-CAM with following code :

(Before trying BME680, I have suscessfully connected BME280 to ESP32-CAM over S/W SPI)

#include <Wire.h>
#include <SPI.h>
#include <Adafruit_Sensor.h>
#include "Adafruit_BME680.h"


#define SEALEVELPRESSURE_HPA (1013.25)

#define BME_SCK 12 //Connected SCL to IO12
#define BME_MISO 15 //Connected SDO to IO15
#define BME_MOSI 13 //Connected SDA to IO13
#define BME_CS 14 //Connected CS to IO14

//Adafruit_BME280 bme; // I2C
Adafruit_BME680 bme(BME_CS, BME_MOSI, BME_MISO, BME_SCK); // software SPI
//float temperature = 0;
//float humidity = 0;
//float pressure = 0;

void setup() {
  Serial.begin(115200);
  while (!Serial);
  Serial.println(F("BME680 test"));

  if (!bme.begin(0x76)) 
  {
    Serial.println("Could not find a valid BME680 sensor, check wiring!");
    while (1);
  }

  // Set up oversampling and filter initialization
  bme.setTemperatureOversampling(BME680_OS_8X);
  bme.setHumidityOversampling(BME680_OS_2X);
  bme.setPressureOversampling(BME680_OS_4X);
  bme.setIIRFilterSize(BME680_FILTER_SIZE_3);
  bme.setGasHeater(320, 150); // 320*C for 150 ms
}

void loop() 
{
  if (! bme.performReading()) 
  {
    Serial.println("Failed to perform reading :(");
    return;
  }
  Serial.print("Temperature = ");
  Serial.print(bme.temperature);
  Serial.println(" *C");

  Serial.print("Pressure = ");
  Serial.print(bme.pressure / 100.0);
  Serial.println(" hPa");

  Serial.print("Humidity = ");
  Serial.print(bme.humidity);
  Serial.println(" %");

  Serial.print("Gas = ");
  Serial.print(bme.gas_resistance / 1000.0);
  Serial.println(" KOhms");

  Serial.print("Approx. Altitude = ");
  Serial.print(bme.readAltitude(SEALEVELPRESSURE_HPA));
  Serial.println(" m");

  Serial.println();
  delay(2000);
}

When I try to upload the code to ESP32-CAM while BME680 is connected I get following error

esptool.py v2.6
Serial port /dev/ttyUSB0
Connecting....
Chip is ESP32D0WDQ6 (revision 1)
Features: WiFi, BT, Dual Core, 240MHz, VRef calibration in efuse, Coding Scheme None
MAC: a4:cf:12:99:b5:70
Uploading stub...
Running stub...
Stub running...
Configuring flash size...
Warning: Could not auto-detect Flash size (FlashID=0xffffff, SizeID=0xff), defaulting to 4MB
Compressed 8192 bytes to 47...

A fatal error occurred: Timed out waiting for packet content
A fatal error occurred: Timed out waiting for packet content

Then I tried to disconnect BME680 and uploaded the code to ESP32-CAM which worked, then connected BME680 back to ESP32-CAM.

But now I see following error in Serial Monitor :

ets Jun  8 2016 00:22:57

rst:0x1 (POWERON_RESET),boot:0x33 (SPI_FAST_FLASH_BOOT)
flash read err, 1000
ets_main.c 371 
ets Jn  8 2016 00:22:57

rst:0x10 (RTCWDT_RTC_RESET),boot:0x33 (SPI_FAST_FLASH_BOOT)
flash read err, 1000
ets_main.c 371 
ets Jun  8 2016 00:22:57

rst:0x10 (RTCWDT_RTC_RESET),boot0x33 SPI_FAST_FLASH_BOT)
lash read err, 1000
et_main.c 371 
ets Jun  8 2016 00:22:57

rst:0x10 (RTCWDT_RTC_RESET),boot:0x33 (SPI_FAST_FLASH_BOOT)
flash read err, 1000
ets_main.c 371 
ets Jun  8 2016 00:22:57

rst:0x10 (RTCWDT_RTC_RESET),boot:0x33 (SPI_FAST_FLASH_BOOT)
flash read err, 1000
ets_main.c 371 
ets Jun  8 2016 00:22:57

Any idea what is wrong here ?

Update :

I switched #define BME_SCK 12 to #define BME_SCK 16, now getting following message

ts Jun  8 2016 00:2:57

rst:0x1 (POWEON_REST),boot:0x13 (PI_FAT_FLASH_BOOT)
cnfigsi: 0, SPIWP:0xee
clk_dv:0x00,q_drv:0x0,d_drv0x00,cs0_drv:0x00,d_drv0x00,wp_drv:0x0
mod:DIO, clock div:
loa:0x3fff0018,len:4
load0x3fff001c,len:1216
ho 0 tail 12 room 4
lod:0x40078000,len:9720
h 0 tail 12 room 4
load0x40080400,len:6352
etry 0x400806b8
[D][esp32-hal-psram.c:47] psramInit(): PSRAM enabled

Answer 1

GPIO12 must not be pulled high during boot. It's possible there's a pull-up resistor on the BME680 breakout board you're using that's pulling SCK high and interfering with the boot process. I would avoid using GPIO12 here.

If you're out of pins on the ESP32 you can connect the BME680 via I2C rather than SPI. I2C only needs SDA and SCK (and power and ground, of course). The Adafruit library for the BME680 has an example of how to call the constructor for an I2C connection.

Answer 2

You use pins

#define BME_SCK 12 //Connected SCL to IO12
#define BME_MISO 15 //Connected SDO to IO15
#define BME_MOSI 13 //Connected SDA to IO13
#define BME_CS 14 //Connected CS to IO14

for software SPI, but the esp32 can use any set of pins for hardware SPI.

And your set of pins are even the dedicated mux pins for SPI2 (they have the direct connection without mux). But they are in different mapping then your software SPI.

SPI2:
SCLK    14  
MISO    12  
MOSI    13
SS      15

Source: https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/peripherals/spi_master.html

SPI2 is the default SPI used by the ESP32 Arduino SPI library, so the Adafruit library should have no problem to use hardware SPI with the SPI library.

Adafruit_BME680 bme(BME_CS); // use hardware SPI

and wire the sensor to SPI2 pins according to their function