pic32mz-eeprom

Working demo of reading and writing from Pic32mz ef starter kit (Pic32mz2048efh144 MCU) to 25LC256 EEPROM via SPI. I found a lot of resources relating to the 25LC256; however, there seemed to be a lack of info using the Pic32mz. The two key files used are eeprom.h and eeprom.c

This repo, which uses an Atmel chip with the same EEPROM, contained simple, clean code and served as a strong influence for interfacing between my mcu and eeprom. I commented out the functions that I didn't test (because I didn't personally need it). This blog also really helped in understanding SPI with Pic32mz.

The demo is writing and reading to/from EEPROM, then outputting the data (from eeprom) via Uart. I sent it to an Arduino board. I'm using SPI1 and my configuration setup for this is in SPI_Init(). This eeprom uses SPI Mode 0, so this is configured by setting:

SPI1CONbits.CKP = 0; // using SPI mode 0 - CPOL = 0
SPI1CONbits.CKE = 1; // using SPI mode 0 - CPHA = 0

This eeprom operates at max 10 MHz, so the SPI clock needs to be lowered in the configuration by setting SPI1BRG. SPI pins (SDI, SDO, SCK, & SS) are configured in this function as well. In eeprom.h, set to match your SS pin:

#define SLAVE_SELECT    LATDbits.LATD0 = 0; // select slave device (low)
#define SLAVE_DESELECT  LATDbits.LATD0 = 1; // deselect slave device (high)

Something to note. I had to wait for the SPI buffer to receive data, so needed to add this after transferring data to SPI buffer via SDO:

while(!SPI1STATbits.SPIRBF);

Resources:

Pic32mz ef starter kit

• Datasheet

25LC256 EEPROM

• Digikey
• Datasheet

Pins Connections (J12 header on starter kit) to EEPROM:

• Pin 2 (5V) to VCC
  • To VCC on eeprom
• Pin 9 (GND)
  • To VSS on eeprom
• Pin 11 (RD0) - Slave Select (SS)
  • To CS on eeprom
• Pin 19 (RF5) - MOSI/SDO
  • To SI on eeprom
• Pin 21 (RF4) - MISO/SDI
  • To SO on eeprom
• Pin 23 (RD1) - SCLK
  • To SCK on eeprom
• Pin 7 (RA14) - configuration commented
  • To HOLD on eeprom. I actually just connected this pin to 5V to keep it high.
• Pin 13 (RJ13) - configuration commented
  • To WP on eeprom. Also connected this pin to 5V to keep it high.
• Pin 8 (RG6) - TX
  • Connected to RX on an arduino.
• Pin 10 (RB14) - RX
  • I didn't use RX to return anything