Generate audio-frequency signals from an MCP4822 dual 12-bit DAC connected via SPI to a PIC32MX550F256L. SPI2 clock at 2MHz, SPI3 clock at 1MHz. New samples sent to DAC at 44.1kHz. SPI3 connects to an OLED display module, 128x64 pixel, based on the SSD1306 chip. SYNC pin set HIGH at beginning of synthesised waveform cycle and LOW at the end.
DAC connections:
| Signal | Chip | Name | Pin | Chip | Name | Pin |
|---|---|---|---|---|---|---|
| SCK2 | PIC32 | RG6/SCK2 | 10 | MCP4822 | SCK | 3 |
| MOSI2 | PIC32 | RC13/SDO2 | 73 | MCP4822 | SDI | 4 |
| SS2 | PIC32 | RD9 | 69 | MCP4822 | CS | 2 |
OLED display connections:
| Signal | Chip | Name | Pin | Chip | Name | Pin |
|---|---|---|---|---|---|---|
| SCK3 | PIC32 | RF13/SCK3 | 39 | SSD1306 | SCK | 3 |
| MOSI3 | PIC32 | RG8/SDO3 | 12 | SSD1306 | SDA | 4 |
| SS3 | PIC32 | RA0 | 17 | SSD1306 | CS | 7 |
| DC | PIC32 | RG9 | 14 | SSD1306 | DC | 6 |
| RES | PIC32 | RE8 | 18 | SSD1306 | RES | 5 |
Digital output:
- SYNC RD0 pin 72
Debugging LEDs on dev board:
- LED1 RE6 pin 4
- LED2 RE7 pin 5
- LED3 RE1 pin 94
- LED4 RA7 pin 91
- LED5 RA6 pin 92
PIC32 pin numbers are for the 100-pin package.
LEDs light when the pin is pulled LOW.
MPLAB X V5.20 and 'xc32' V2.15. These are quite old versions now, so I really ought to upgrade!
Microchip ICD3. Other programmers should work, e.g. ICD4 or PICkit4.