I like to play with both Arduino and other boards in Arduino form factor. And I find a great thing to be able to create complicated projects by stacking a number a pre-made shields. However, sometimes I ran into trouble: there are conflicts between shields that use the same Arduino pins for their control signals. Other times I have issues with Arduino-compatible boards having the SPI and I2C signals mapped differently from the original Arduino.
Here comes into play one of the most useful shields in my inventory: the Go-Between shield. Technically this shield isolates the top and bottom pins, and provides an interconnecting matrix of pads that allows us to perform a remapping of Arduino pins. This remapping is achieved by placing solder bridges on the appropriate pads. The shield is reusable too: just use some solder wick to remove the bridges. As an advice, I usually place the board to be remapped on top, and I place only the required solder bridges for that board to work. Thus, when I want to reuse the go-between shield all I have to do is to take some solder wick and remove the old bridges.
Some ideas to use the Go-Between shield:
The Go Between shield has a lot of possible uses. Here are some examples that I find particularly useful:
Controlling four motors
You can easily stack two Ardumoto shields by Using the Go-between shield to perform a pin remapping of the top shield.
As such, the bottom Ardumoto shield will have the standard pin mapping:
PWMA1 – Pin 3
PWMB1 – Pin 11
DIRA1 – Pin 12
DIRB1 – Pin 13
For the top shield we will use the following pin mapping:
PWMA2 – Pin 10
PWMB2 – Pin 9
DIRA2 – Pin 8
DIRB2 – Pin 7
The following bridges must be places on the Go-between shield to perform this mapping:
– top digital pin 3 to bottom digital pin 10
– top digital pin 11 to bottom digital pin 9
– top digital pin 12 to bottom digital pin 8
– top digital pin 13 to bottom digital pin 7
Don’t forget to change the code also to reflect the new pin mappings!
Using Ardumoto with ChipKit Uno32
The ChipKit Uno32 development board from Digilent does not have PWM capability on Pin11. Although you can modify the board to use Pin 10 for PWMB, this modification requires some experience in soldering. An easier alternative is to perform a remapping of Pin 11 to Pin 10 by inserting a Go Between shield between the ChipKit Uno32 and the Ardumoto, with the following solder bridges:
– top digital pin 3 to bottom digital pin 3
– top digital pin 11 to bottom digital pin 10
– top digital pin 12 to bottom digital pin 12
– top digital pin 13 to bottom digital pin 13
Please observe that this are only the required bridges for the Ardumoto. If you plan to install other shields, please make the appropriate solder bridges.