OLED Assembly
An issue has been discovered with the Trinket Pro (SRAM size). We are currently in the process of switching microntrollers, DO NOT REPLICATE THIS ASSEMBLY AT THIS CURRENT TIME.
First off, you'll probably want to solder headers to the serial FTDI Header at the end of the Trinket to connect to a computer and flash code to the Trinket. You can simply solder the headers provided by Adafruit, then use a USB-TTL cable (https://www.amazon.com/USB-to-TTL-Serial-Cable/dp/B00N2FPJ0Q).
Now that you've got a connection to the Trinket, flash the latest version of the OLED code to the Trinket.
For connecting the Trinket to the OLED, we need to simply solder the appropriate pins on the Trinket to the OLED. The OLED pins are numbered left to right (1 and 20 are visibly numbered), and the Trinket's pins are numbered according to the following pinout: Trinket Pinout.
Another preparation step is to make sure that the OLED is on SPI mode. It should come this way, but please check. You could use it in I2C mode, if you want, but none of this assembly will be relevant. Please see the following page for information (SPI/I2C for 2.4 OLED).
The connection is as follows:
- Pin 1 (OLED Power) to 3V output on Trinket. (See capacitor note).
- Pin 2 (OLED Ground) to GND Trinket. (See capacitor note).
- Pin 4 (OLED DC) to digital pin 8.
- Pin 7 (OLED Data 0/SPI Clock/ SCLK) to digital pin 13 (SCLK).
- Pin 8 (OLED Data 1/DIN/MOSI) to digital pin 11 (MOSI).
- Pin 15 (OLED CST) to digital pin 10.
- Pin 16 (OLED RST) to digital pin 9.
Based on guidance from Adafruit, we recommend that you place a 220uF capacitor over the power input for the OLED. This is meant to make up for power fluctuations in the 3V output from the Trinket. You can simply use the capacitor provided by Adafruit, and solder it inline on the way to the OLED.
The Trinket needs to be provided with power and connected to the Jetson via serial cable. We have a pair of wires soldered to the input power lines on the Trinket which can be attatched to a power supply from the PDB in the rear. Additionally, we have a cable soldered to TX and RX on the Trinket, which can simply be attached to a TX/RX pair on the Jetson carrier board. On the Orbitty, these are in the GPIO header.
Currently, we are mounting the OLED screen to a 3D printed mount in the robot's internals, but leaving the Trinket Pro hanging by its cables. This works for us because the cables are stiff enough that they can keep the Trinket Pro relatively stable. However, if this does not work for you, we would recommend that you either screw the Trinket directly to the MDF or attach it with velcro.