Assemble Main Board V1.3a
The V1.3a release of the UKMARSBOT main board brings some minor updates. The build guide is substantially unaltered but these additional notes by Chris Balmforth may help:
Version 1.3 of the Main PCB introduced some improvements:
- Positioning of the half size sensors has been improved with the mini wide line sensor pcb, and slots cut in the main PCB to allow them to illuminate the track.
- Electrolytic capacitors C2 and C3 have been added to smooth out motor power surges. These should be no larger than 8mm diameter x 11mm high or you will have difficulty inserting the programming lead. The indicator led and current limiting resistor have been removed to make room for these, but that function is fulfilled by the Nano’s built-in led.
- There are now just two battery connector lead pads for simplicity. Either solder a PP9 battery lead here or a polarised 2-pin connector depending on the battery you are using.
- Some builders are experimenting with updated versions of the Arduino Nano which operate with a 3V3 logic level. A 74HC86 is now suggested for IC1 instead of a 74LS86 as it is compatible with both 3V3 and 5V logic.
- The values of step-down resistors R7 and R8 can be changed to allow future use of 3V3 Nano variants. 33K and 10K respectively will be safe to use with 3V3 logic up to a 3 cell lithium battery.
- There have also been some minor changes to tidy up component layout.
- This is the v1.3 main pcb top and bottom view:
