TinyTX4_BME280

This Arduino IDE sketch is for a TinyTX4 Tranceiver from meigrafd to read and transmit the BME280 I2C humidity, pressure and temperature sensor data to the TinyRX4 Receiver.

Based on Sketch from meigrafd: https://github.com/meigrafd/TinyTX4

TinyTX4 / TinyRX4 meigrafd Project-Page: https://forum-raspberrypi.de/forum/thread/7472-batteriebetriebene-funk-sensoren/

Thanks to technoblogy for the very tiny 'tiny-bme280' library, which I have implemented in the sketch: https://github.com/technoblogy/tiny-bme280

Make sure that your BME280-Board supports 5V power input. Some boards, such as Adafruit's, support either 5V or 3.3V operation, so check before.

Don't forget the pull-up resistors (4,7KOhm) on SCL and SDA.

The expected default I2C-slave address is 0x76. You can change it in the sketch (BME280address) if necessary.

Compiling and programming the Attiny84 with Arduino IDE

The following librarys are needed to compile the sketch:

• RFM12B : https://github.com/LowPowerLab/RFM12B/archive/master.zip

• SoftI2CMaster: https://github.com/felias-fogg/SoftI2CMaster

I compiled the sketch in following enviroment:

• Arduinon IDE Version 1.8.5

• ATTiny Core from SpenceKonde: https://github.com/SpenceKonde/ATTinyCore with following configurations:

  • Board: ATtiny24/44/84
  • Pin Mapping: Counterclockwise (like old ATTinyCore and x41-Series)
  • Chip: ATtiny84
  • Clock: 8 MHz (internal)
  • EEPROM: EEPROM retained
  • LTO (1.6.11+ only): Enabled
  • B.O.D. Level: B.O.D. Disabled
  • Programmer: Arduino as ISP (ATTiny Core)

• Arduino Nano V3.0 clone as ISP

  • Upload the Sketch 'ArduinoISP' from examples to the Arduino
  • set Board to ATiny84 Hardware as described above
  • Burn Bootloader on the ATtiny84
  • Upload sketch to Attiny84

If you run in to an error like: 'avrdude: stk500_getsync(): not in sync: resp=0x15' already at burning bootloader.
Try an 10µF Capacitor between Arduino RESET and GND pin while programming the ATtiny84.

ATtiny84 PIN Configuration

SDA, SCL, LED and SensorPower pin can be changed in the sketch if necessary

                           +-\/-+
VCC                  VCC  1|    |14  GND           GND
---             (D0) PB0  2|    |13  AREF (D10)    SensorPower(BME280)
nSEL(RFM12B)    (D1) PB1  3|    |12  PA1 (D9)      LED
---                RESET  4|    |11  PA2 (D8)      SCL(BME280)
nIRQ(RFM12B)    (D2) PB2  5|    |10  PA3 (D7)      SDA(BME280)
---             (D3) PA7  6|    |9   PA4 (D6)      SCK(RFM12B)
SDO(RFM12B)     (D4) PA6  7|    |8   PA5 (D5)      SDI(RFM12B)
                           +----+