PIC18F47Q10 Using TMR2 as Alternate SPI clock

The PIC18F47Q10 features Three 8-bit Timers/Counters and two MSSP modules, which can be configured in SPI mode. In this demo, the TMR2 is used as 10kHz clock for SPI, configured as host with 2 clients (RC6 pin ->SS1 and RC7 pin ->SS2).

Related Documentation

• TB3285 - Getting Started with Timers/Counters on PIC18
• PIC18F47Q10 Product Family Page
• PIC18F47Q10 datasheet
• TB3261 - PIC1000: Getting Started with Writing C-Code for PIC16 and PIC18

Software Used

• MPLAB® X IDE 5.30 or newer (microchip.com/mplab/mplab-x-ide)
• MPLAB® XC8 2.10 or newer compiler (microchip.com/mplab/compilers)

Hardware Used

• PIC18F47Q10 Curiosity Nano (DM182029)
• An oscilloscope or logic analyzer

Setup

The PIC18F47Q10 Curiosity Nano Development Board (DM182029) is used as the test platform.

The following pin configurations must be made for this project:

Pin	Configuration
RC3	Digital output SCK
RC4	Digital input SDI
RC5	Digital output SDO
RC6	Digital output SS1
RC7	Digital output SS2

Operation

1. Calculate the SCK frequency using the formula frequency = 1/Timer2Period/2.
2. For example for 10kHz frequency = 1/50μS/2 = 10 kHz, this means Timer2Period = 50μS.
3. Build demo firmware, make and program the generated code onto the PIC18F47Q10 Curiosity Nano.
4. Run the code, connect an oscilloscope or logic analyzer to the pins:

• RC3 pin - SCK -> Channel 1 (blue)
• RC6 pin - SS1 -> Channel 2 (red)
• RC7 pin - SS2 -> Channel 3 (green)

5. In the screenshot below, the SCK frequency is 10 kHZ (blue signal).
   

Summary

This project showcases how easy it is to use the TMR2 of PIC18F47Q10 as Alternate SPI clock.