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HeaterMeter 3.0 Hardware

CapnBry edited this page Sep 5, 2012 · 1 revision

As a reminder, HeaterMeter refers to the ATmega (Arduino) based microcontroller board that runs the LCD, reads button and temperature probe inputs, and controls the blower motor. This document describes the configurations and design of the HeaterMeter board, which may optionally be installed into an OpenWrt-compatible router to become a LinkMeter.

Standard HeaterMeter hardware is built on a HeaterMeter V3.2 PCB


There are two possible major HeaterMeter configurations. Both designs are fully interchangeable but some components can omitted if not needed.

Standalone HeaterMeter

Original HeaterMeter configuration for use without an OpenWrt router. Provides automatic grill control, and LCD display. Initial configuration is via serial commands. Set Point, manual fan mode, probe offsets, open lid detect and max fan speed configurable via buttons. There is integrated no web access or graphs, but there is a serial status output to allow you to roll your own solution.

Standalone HeaterMeter adds a barrel power jack and can omit the pinhead power jack, router serial output, and self-reset circuit.

HeaterMeter for LinkMeter

The HM for LM (HM4LM) configuration doesn't need the barrel power jack, and adds a pinhead power jack, router serial output, and self-reset circuit. HM4LM still runs the ATmega microcontroller at 5V supply, however the design can be adapted for pure 3.3V supply, which runs off the 3.3V from the router. 5V is used for better ADC resolution and for use with a 5V LCD display, which seem to be more prevalent than their 3.3V counterparts.

Parts List

Parts Complete Build V3.2 PCB

Qty Value Device Parts Link
1 ATmega328P AVR-MEGA8-PPTH IC2 Mouser
1 74HC595N 74HC595N IC3 Mouser
1 16Mz RESONATOR-PTH Y1 Mouser
1 0 R-US_0204/7 R7 AKA a wire
1 390 R-US_0204/7 BTN-R7 Mouser
1 680 R-US_0204/7 BTN-R8 Mouser
4 1k R-US_0204/7 R1, R3, R15, R19 Mouser
1 2.2k R-US_0204/7 BTN-R9 Mouser
6 4.7k R-US_0204/7 R2, R13, R22, R23, R24, BTN-R11 Mouser
5 10k R-US_0204/7 R20, R21, R25, R26, R27 Use %1 below
4 10k 1% R-US_0204/7 R5, R16, R17, R18 Mouser
1 10k TRIM_US-CT6 R6 Mouser
1 10k THERMISTOR_R-2,5 TR1 Mouser
1 0.01u C-US025-025X050 C7 Mouser
5 0.1u C-US025-025X050 C2, C3, C6, C9, C10 Mouser
1 22u/6.3 CPOL-USE2.5-6 C8 Mouser
1 22u/25 CPOL-USE2.5-6 C1 Mouser
1 47u/10 CPOL-USE2.5-6 C5 Mouser
1 47u/25 CPOL-USE2.5-6 C4 Mouser
2 1N4001 DIODE-DO41-7 D1, D3 Mouser
1 1N5817 DIODE-DO41-7 D4 Mouser
1 IRL510 PMOSFET_NTO220BV Q1 Mouser
1 BC337 BC337 Q2 Mouser
1 7805 7805TV Q3 Mouser
1 MCP1700-33 MCP1700TRI Q4 Mouser
1 GRN LED3MM LED1 Mouser
1 RFM12B RFM12B U$1 ModernDevice Extremely optional!
1 LCD_16X2 TUXGR_16X2_R2 DIS1 Mouser


Qty Device Parts Link
1 Male PINHD single row J1(LCD), J2(PROBE), J3(BTN), J4(BLW), J8(FTDI) Mouser 0.23" mate/0.12" tail/15u gold
2 CONHOUSE single row 6-pin P1(LCD 2x) Pololu (or 6x 2-pins)
1 CONHOUSE single row 5-pin P2(PROBE) Pololu
2 CONHOUSE single row 2-pin P3(BTN),P4(BLW) Pololu
1 Female PINHD 1X6/90 P5(RTR) DigiKey
1 Male PINHD 2x3 J6(ICSP) Mouser
1 Male PINHD single row/90 J7(POW), PX5(RTR External) Mouser
1 Crimp pins female x100 N/A Pololu
1 2.1mm POWER_JACKPTH J9(POW) Mouser
4 Mono 2.5mm female jack JP3(PIT), JP4(FOOD1), JP5(FOOD2), JP6(FOOD3/AMB) Mouser
1 RCA Female jack JX4(BLOWER External) Mouser

Probes and Fan

Qty Description Link
1 Blower-style fan 12VDC 5-10CFM DigiKey
1-4 Maverick BBQ Thermistor Probes (3ft or High Heat) Maverick

Mouser Project for all Mouser parts listed above $34.08

Parts HeaterMeter Standalone

  • Enclosure Mouser
  • 12VDC/600mA power brick 5.5x2.1mm barrel jack. 500mA may be ok Sparkfun

Wireless Probe Support

To use wireless probes, a RFM12B receiver needs to be added to the design. These parts are included in the list above. The default code assumes a 915MHz transceiver, which is only legal in the United States, but a one-line code change facilitates using 433MHz or 868MHz bands to comply with other local regulations. In the Standalone HeaterMeter configuration, an additional 3.3V power supply needs to be added to power the transceiver. The 3.3V regulator is not needed in the HM4LM configuration.

If you do not wish to have wireless probe support you can omit a large number of parts: R22 through R27, U$1, Q4, C8 and C9. R15 and LED1 are also optional but recommended for debugging purposes because LED1 is blinked once before initialization and once after.

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