GPIO on both Linux and TI-RTOS with DRA726 processor

Michel Catudal

Other Parts Discussed in Thread: SYSBIOS, DRA726

I have code running in TI-RTOS on the Cortex M4 and in Linux on the Cortex A15.

How do I read and write GPIO ports? This is for bit banging.

Assume that all the bits are on the same GPIO port for your answer,

I need to test some Microchip devices on the evaluation board and have no SPI available. I will have them on the design but for now I need to bitbang the SPI.

I will need to access GPIO as outputs and inputs in both M4 and Linux beside this. My LIN driver needs to do some bit banging since there is no LIN port on this device.

Example below

Not likely the GPIO or bits I would use, just so you understand what I mean :

GPIO2 bits 0 and 5 on Linux

GPIO2 bits 1 and 4 on TI-RTOS on Cortex M4

Michel

over 9 years ago

0 Aldabreu over 9 years ago

TI__Intellectual 2890 points

Hi Michel,

Which version of TI-RTOS/SYSBIOS are you using to run your application on the M4 core?

Best,
Alexander

0 Michel Catudal over 9 years ago in reply to Aldabreu

Genius 3825 points

Right now I am writing the software specs for the project. In our proof of concept project (prove that it was a good move to use TI instead of Freescale) During that POC we used the previous SDK which was using an older version of CCS. I plan to use the latest SDK that was released in July. It looks like it uses the latest CCS. We have the 2 local CAN code running on the Cortex M4 and some IPC code on Linux to interface with Embedded Wizard which uses weston for its display.

My SDK will be a modification of the one created using those instructions, our hardware will be quite different than this one, partly based on the automotive evm with our addition to support a co-processor. Flash will be on NOR and eMMC. NOR will be on the quad spi.

processors.wiki.ti.com/.../Processor_SDK_Building_The_SDK

I am using the evm based on the beagleboard x15 right now but will get hardware with the DRA726 in November. It is close enough for several parts of the code, better than using a simulator.

I hope this answers your question.

Do you have a different SDK project for the DRA726?

Michel

0 ToddMullanix over 9 years ago in reply to Michel Catudal

TI__Guru* 96960 points

I've moved your thread to the device forum. I think they'll be able to answer your question better.

Todd

0 Lyudmila Kamenova over 9 years ago in reply to ToddMullanix

TI__Intellectual 1285 points

Hi Mickel,

Your question has been forwarded to a SW expert.

Best regards
Lucy

0 Nikhil Devshatwar over 9 years ago in reply to Lyudmila Kamenova

TI__Genius 9905 points

Starterware has following APIs, you can use them for bitbanging the GPIO lines.

void GPIOModuleEnable(uint32_t baseAdd);

void GPIODirModeSet(uint32_t baseAdd, uint32_t pinNumber, uint32_t pinDirection);
void GPIOPinWrite(uint32_t baseAdd, uint32_t pinNumber, uint32_t pinValue);

Refer to starterware_/include/gpio_v2.h

0 Michel Catudal over 9 years ago in reply to Nikhil Devshatwar

Genius 3825 points

Nikhil,

You didn't answer my question. I want to know if I can set on particular GPIO in TI-RTOS as well as DRA726.

In other words, if I access a bit on Linux can I access another bit on that port in TI-RTOS on the DSP or Cortex M4 without keeping the other core from accessing the bit(s) that it wants to use?

Michel

0 Nikhil Devshatwar over 9 years ago in reply to Michel Catudal

TI__Genius 9905 points

Yes, you can access the GPIO module once linux has initialized it.

Linux being intelligent, will turn the module off if nobody is using it.

So you need to tell linux that there is a dummy user of the GPIO line(gpio-hog) to avoid clock being cut.

This way, The module will always be on.

You can read from other core running RTOS, BUT do not change any GPIO.

Device partitioning assumes that GPIO is controlled by linux, do not confuse the driver via unknown accesses from DSP/M4.

Regards,

Nikhil D

0 Michel Catudal over 9 years ago in reply to Nikhil Devshatwar

Genius 3825 points

Thank you

Michel

Processors

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GPIO on both Linux and TI-RTOS with DRA726 processor