Front view of expansion Header:
Here is a rear view diagram of the pin header taken from the badge schematic.
These pins can be controlled from BASIC using the edir, ein, and eout commands. The UART on pins C13 and C14 can be accessed from BASIC using uin and uout commands.
G2 and G3 are 5V tolerant but all other pins should be interfaced at 3V.
Important: there is no voltage regulation on the badge, and the PIC32 datasheet lists maximum Vdd of 3.6. Keep this in mind if upgrading power supply beyond a pair of AA batteries. (A fully charged lithium ion battery tops out at 4.2V.)
New for the Hackaday Supercon is a hardware expansion board for prototyping your own circuits. Pictured here is the prototype. The final design will be black, and it will include three headers for #Shitty Add-Ons
To the right there will be a mounting hole so that the expansion board can be firmly affixed to your badge.
Here is the front view (red) and rear view (green) of the circuitry for the expansion board. Here is the list of package footprints available:
- 3 × Shitty Add-On headers
- 1 × SO-8
- 1 × SO-16
- 1 × TSSOP-16
- 2 × SOT-23 (for SMD transistors)
- 14 × 0805 (for SMD passive components)
- 1 × LGA-16 (for accelerometer only)
All round pads are general purpose pads, and square ones are connected and intended for special use. The following drawing contains color marking for those pads, so the black pads are Ground (0V) connection, red pads are for +3V supply, green ones are I2C Clock pads, and blue ones are I2C Data pads. They are arranged so that you can use up to three shitty-add-on connectors without any modification of the PCB.
Pull-Up Resistor Footprints for I2C
If you plan to use I2C (for your own circuit or for a shitty-add-on), pull-up resistors must be added. Please note that there are no pull-up resistors for the I2C bus on the main board, so you should add 4K7 (or similar) pull-up resistors on the noted 0805 footprints at the column "t", rows 4-5 and 6-7. Those 0805 footprints are marked as DA (data) and CK (clock).
Adding an Accelerometer
If you add an LIS3 accelerometer to your expansion board, it is highly recommended to add the ceramic capacitor at the column "q", rows 4-5. Its capacitance should be 4.7 to (preferably) 10 µF.
Pin 1 of the accelerometer is at the bottom left. Only LIS3DH or LIS3DE accelerometers can be used, as the pads on the LGA-16 footprint are connected to required sources. Please note that LIS3DH and LIS3DE have the same pinout diagram, but they are many internal differences, including register and slave addresses. For instance, LIS3DH has 16-bit output reading for each axis, and LIS3DE has 8-bit outputs.
Other Footprints on the Expansion Board
There are 18 large square pads at the bottom layer of the PCB. All those pads are general purpose and are convenient for attaching large components or thick conductors.
Leftmost and rightmost columns "A" and "v" can be used for SIL connectors. Holes on these pads are with 1mm diameter, so they can accept normal male pins of SIL headers.