Temperature and auxiliary sensor (RS485)

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Temperature and auxiliary sensor

Temperature sensor with RS485 interface. Uses an AVR ATmega8 microcontroller.

I/O

Inputs

  • PC0 Temperature sensor (analog)
  • PC1 Temperature humidity (analog) [in 1]
  • PC2 Temperature auxiliary (analog) [in 2]
  1. ↑ Not connected
  2. ↑ Not connected

Calculations

Temperature
Humidity

Outputs

  • PB0 Life signal
  • PB1 Link RX activity
  • PB2 Link TX activity

Serial communication

  • PD0 Rx
  • PD1 Tx
  • PD2 Mode

Communication

Interfacing is done with RS-485, using MAX485.

Serial settings

Baud
38400
Data bits
8
Parity
None
Stop bits
1

Source code

Git-alt-brands.svg
Bascom-AVR source is available in a git repository:
https://github.com/thomasjsn/AVR-Temp-aux-sensor-RS485

Gallery

  • Temp aux sensor rs485-20120217 203219.jpeg
  • Temp aux sensor rs485-20120217 205613.jpeg
  • Temp aux sensor rs485-20150918 234449.jpeg
  • Temp aux sensor rs485-20150918 234523.jpeg
  • Temp aux sensor rs485-20150918 234535.jpeg
  • Temp aux sensor rs485-20150918 234543.jpeg
  • Temp aux sensor rs485-20150918 235615.jpeg
  • Temp aux sensor rs485-20150918 235621.jpeg
  • Temp aux sensor rs485-20150918 235628.jpeg
  • Temp aux sensor rs485-20150918 235639.jpeg
  • Temp aux sensor rs485-20150918 235656.jpeg
  • Temp aux sensor rs485-20150918 235707.jpeg
  • Temp aux sensor rs485-20150918 235718.jpeg
  • Temp aux sensor rs485-20150918 235730.jpeg
  • Avr-to-rs-485-using-max485-8g2rlq.png

Schematic diagram

AVR-temperature-sensor-RS485-circuit.png

Parts used

Qty. Part
1 × AVR ATmega8-16PU, DIL-28, 16 MHz, 23 I/Os
2 × Capacitor, aluminium electrolytic, 10 µF, 25V
2 × Capacitor, aluminium electrolytic, 47 µF, 25V
3 × Capacitor, ceramic, 1 nF, 100V
3 × Capacitor, metallized polyester foil, 10 nF, (0.01 µF)
1 × DIL socket, 28-pin, 7.62mm
1 × DIL socket, 8-pin, 7.62mm
1 × Enclosure, plastic (1591), 120x120x59mm
1 × Fuse 5x20 mm, 500 mA, fast-acting
1 × Fuse holder, open, PCB, 5x20mm
1 × Fuse holder, open, PCB, Protective cover
1 × Heatsink, 27.3K/W, 19mm, attachable, TO220
1 × LED 5mm coloured clear, Green, 2.1V, 20mA, 30mcd, 10°
1 × LED 5mm, Red, 2.0V, 20mA
1 × LED 5mm, Yellow, 2.0V, 25mA
3 × LED holder 5mm, RTC51, black plastic
64 cm2 PCB, stripboard, 100x160mm, 160cm2
1 × Power jack, panel, 2.1mm, plastic housing
1 × Resistor, carbon film, 0.25W, 100 Ω, 5%
3 × Resistor, carbon film, 0.25W, 330 Ω, 5%
1 × RS422/485 interface, MAX485CPA, HDX, 2.5 Mbps
1 × Spacer, round unthreaded, 3mm, Ø6mm, Delrin
2 × Spring-loaded terminal block, PCB, 0,5 mm2
2 × Straight pin header, female, Dual row, 2.54mm
22 × Straight pin header, female, Single row, 2.54mm
32 × Straight pin header, male, Single row, 2.54mm
1 × Temperature sensor LM35DZ, 0 to +100 °C, +-0,6 °C
1 × Voltage regulator +5V, 2 A, L78S05CV
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