C2000, 8305 SPI Chip Select Pin Conflict

Hector Hernandez Luque

Hi to all,

I am utilizing a C2000 28027F interfaced with a 8305. Previously the two were interface with GPIO19 setup as

GPIO_setMode(obj->gpioHandle, GPIO_Number_19, GPIO_19_Mode_SPISTEA_NOT);

The issue that I am facing now is that my design requires the use of an Ecap pin, and GPIO5 is being utilized for a PWM signal (driving a motor). This left only GPIO19 as the other possible Ecap pin and thus a conflict came about.

This is a designed PCB where I took for granted the Chip Select function as a simple GPIO operation and interfaced the 8305 Chip Select signal with GPIO34 of the C2K. I am currently wondering if it is possible to use the SPI Chip select as a GPIO high signal when necessary. Any assistance or direction is greatly appreciated.

over 10 years ago

0 Mark Labbato over 10 years ago

Guru 30330 points

Hector,

I am not sure I understand the issue here. Is the 8305 chip select currently wired to GPIO19 or GPIO34? You mention that you have an already design PCB, what does that connection look like? Can you modify your wiring in any way?

-Mark

0 Hector Hernandez Luque over 10 years ago in reply to Mark Labbato

TI__Expert 8985 points

Hi Mark,

Currently I have GPIO19 setup as ECAP1 and GPIO34 as a GPIO. I would like to verify if I can use GPIO34 as a SPI Chip Select pin by driving it high or low when necessary.

0 Hector Hernandez Luque over 10 years ago in reply to Hector Hernandez Luque

TI__Expert 8985 points

The PCB traces are designed with SPI Chip Select from 8305 going to GPIO34

0 Mark Labbato over 10 years ago in reply to Hector Hernandez Luque

Guru 30330 points

Hector,

If the F28027F is the SPI master, then yes, there is no problem with this. There are many posts here on E2E on using a GPIO as the Chip select.
If F28027F is the SPI Slave, then you must use GPIO19 as this is the only place where the function is brought out to a pin.

-Mark

0 Hector Hernandez Luque over 10 years ago in reply to Mark Labbato

TI__Expert 8985 points

Thank you. The C2000 is the master. I setup the SPI Chip Select as GPIO34 and pull up voltage before the write/reading starts and pull down after finishing. Need to test.

0 Mark Labbato over 10 years ago in reply to Hector Hernandez Luque

Guru 30330 points

Great! Please let me know if that has fixed your problem. If so, don't forget to close out the thread by verifying the answer.

-Mark

C2000™︎ microcontrollers

C2000 microcontrollers forum

C2000, 8305 SPI Chip Select Pin Conflict