Converting a UKMARSBot to a Raspberry Pi Pico from a Arduino Nano - PART 1

This refers to the UKMARSBot detailed here https://github.com/ukmars/ukmarsbot

 

 

 

 

 

 

 

 

 

This picture is the original before it was modified - it had two custom modifications - the LED that replicates the on-board Arduino LED D13 has been replaced by a buzzer (left of top wheel), and an IMU (accelerometer/gyroscope) has been fitted onto unused pins from the Sensor board. It also has the optional Bluetooth module fitted (left of bottom wheel).

Several other people have converted this done this in various ways, this is my take on it.

What needs to be changed?

Well, the board is better to run off 3.3v rather than 5v. Mostly this should be okay, and was discussed in https://youtu.be/_E6mRQq4exo?t=1071 by Peter Harrison on a UKMARS virtual meeting.

The first two things to sort out first are:

• Replacing the 74LS86 to a 74HC86 Exclusive-OR gate
• Changing the battery measurement potential divider

  

74LS86 Replacement

 

(slightly blurry - it's not your eyes!)

 

If you have already built the board, removing this is a bit of a pain. I seriously considered just building another UKMARSBot from scratch. However the proper tool - in my case a heated 'Desoldering Pump' (£15.20 from Amazon) - makes it much easier.

 

The replaced part:

 

The resistor - Peter suggested soldering an additional resistor. I decided to use my new Desoldering Pump, and replaced the 'upper' resistor R7 10K with a 22K resistor.

 

 

In part two we will continue the modifications....

 

References

https://ukmars.org/2021/02/a-raspberry-pi-pico-based-ukmarsbot/

https://ukmars.org/2020/12/alternative-processors-for-ukmarsbot/