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The Aux (Auxillary) board houses various less commonly used features that would not fit on the lettuce core board:

Description [size] Format
Circuit schematic [6.3KB] Adobe Acrobat PDF
PCB layout [44.4KB] Adobe Acrobat PDF

The temperature sensor used is a Microchip TC1047A - a linear output sensor which is connected via the AUX connector to an analog input on the core board's processor. The sensor has a range of -40 to +125 degrees Celcius and a typical accuracy of +/- 0.5 degrees Celcius.


The plugin is designed to interface with the Lettuce-v1 core board via the AUX header.

Timer/counter input header

The timer/counter input connector is implemented as follows:

Pin Name Purpose
1 TICK Timer/counter input
2 Vdd +3.3v supply
3 Gnd Ground

PWM output header

The PWM output connector is implemented as follows:

Pin Name Purpose
1 PWM PWM output
2 VddPWM PWM power
3 Gnd Ground

Note: this is designed to allow a Futaba-style servo to be directly connected.

PWM power header

This can be used to supply external power to be used by the PWM outputs.

The PWM power connector is implemented as follows:

Pin Name Purpose
1 +3.3v Internal 3.3v supply out
2 VddPWM PWM power in
3 Gnd Ground

Note: External power supply should be connected using pins 2-3. To use internal 3.3v supply, place jumper across pins 1-2.

Component list

Below is a full list of components required to build the RS-232/LIN plugin board.


ID Value Package Description
U1 TC1047A SOT-23 Temperature sensor
U2 LM393 SO8 Dual comparator


ID Type Description
J1 2x4 100mil R/A socket Core AUX socket
J2 1x3 100mil header PWM output 1
J3 1x3 100mil header PWM output 2
J4 1x3 100mil header Timer/counter input 1
J5 1x3 100mil header Timer/counter input 2
J6 1x3 100mil header PWM external power


ID Value Package Description
R1 470R 0805 LED limiter
R2 10K 0805 Voltage buffering
R3 10K 0805 Voltage buffering
R4 10K 0805 Voltage buffering
R5 10K 0805 Voltage buffering
Updated on 2010-04-25 13:42:21 +0000 | Requested on 2022-12-02 15:40:19 +0000