Boot from flash pin configuration on TMS320F28035

Gloria Budiman

I'm developing using bare-microcontroller (that is, without control card or control stick). I need the microcontroller to boot to flash upon power-up. From what I read on the documentation here -> http://www.ti.com/lit/pdf/spraas1 (page 22), I need to have GPIO18, 29, and 34 tied high during start-up. The problem is, those 3 pins are connected to external peripherals in my project.

My question is, when the device starts up, is the GPIO defaulted to high-impedance, or some other state? If it's default to high-impedance, would adding pull-up resistor on those 3 pins allow the MCU to boot from flash upon startup?

Thanks

over 13 years ago

0 Manoj Santha Mohan over 13 years ago

TI__Guru 55700 points

Gloria,

You are referring to a wrong document. Please refer TMS320x2803x Piccolo Boot ROM Reference Guide (Rev. A)

To "BOOT to FLASH" you need to pull up GPIO34 and GPIO37 and program 0x3D 7BFE with 0x55AA.

Regards,

Manoj

0 Gloria Budiman over 13 years ago in reply to Manoj Santha Mohan

Intellectual 815 points

Upon power-up, would GPIO34 and GPIO37 be in high-impedance? And if I'm not mistaken, it has internal pull-up resistor, so it will be pulled-up high upon power-up?

Also, programming 0x3D7BFE would mean I have to include codeStartBranch.asm into the project during compile time, is that correct?

Thanks

0 Manoj Santha Mohan over 13 years ago in reply to Gloria Budiman

TI__Guru 55700 points

Yes, I believe both GPIO34 & GPIO37 have an internal pull up resistor.

I am not sure for programming 0x3D7BFE why you need to include codeStartBranch.asm.

Regards,

Manoj

0 Gloria Budiman over 13 years ago in reply to Manoj Santha Mohan

Intellectual 815 points

Because I'm not sure on how to program 0x3D7BFE with 0x55AA

0 Manoj Santha Mohan over 13 years ago in reply to Gloria Budiman

TI__Guru 55700 points

Gloria,

This should be easy. In your existing project open a .asm file and include it into your project.

Contents of asm file:

        .sect "OTP_KEY"
        .int 0x55AA

        .sect "OTP_BMODE"
        .int 0xFFFF

Now, you have to change the linker command file (.cmd file) as shown below:

OTP_KEY : origin = 0x3D7BFE, length = 0x000001 /* OTP_KEY */
OTP_BMODE : origin = 0x3D7BFF, length = 0x000001 /* OTP_BMODE */

Compile the code and program the .out file in Flash/OTP. This should have programmed 0x55AA in 0x3D7BFE.

Hope that helps.

Regards,

Manoj

0 Gloria Budiman over 13 years ago in reply to Manoj Santha Mohan

Intellectual 815 points

Sounds weird but CCS 4 does that automatically?

0 Manoj Santha Mohan over 13 years ago in reply to Gloria Budiman

TI__Guru 55700 points

Unlike CCS3.3v where you have to use On Chip flash programmer to program flash CCS4 just uses Load Program to program the code in RAM (or) FLASH. So, it is not surprising to see the contents getting programmed automatically.

-Manoj

0 Gloria Budiman over 13 years ago in reply to Manoj Santha Mohan

Intellectual 815 points

Something weird happens.

If I plug the JTAG (CCS not running), the code in my FLASH executes correctly.

However, as soon as I unplug the JTAG after power cycle, the code doesn't run at all. Wondering what's been wrong?

Thanks

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Boot from flash pin configuration on TMS320F28035