TM4C1294NCPDT ROM Bootloader Setup - Quick Question

Hello Bryan

The ROM Boot Loader does not need the bl_config.h file. This file is meant only when using the Flash based bootloader.

Regards
Amit

Hello Amit,

Thanks for your reply! So how should I proceed when utilizing the ROM based bootloader to update via UART? By my understanding I should use the following procedure:

1. Program the BOOTCFG Register with my desired settings
2. Apply the boot signal to the GPIO that I specified in the BOOTCFG Register
3. Send commands/packets to the ROM Bootloader as described in Tivaware Bootloader User's guide (spmu301a)

Does the ROM Bootloader automatically configure the UART pins to receive commands?
Does the ROM Bootloader default to use autobaud with the UART connection?

Best Wishes,
Bryan

Hello Amit,

I understand now! Thank you for the clarification and quick responses as usual! Have a great day.

Cheers,
Bryan

Hello Amit,

I just realized there was one last thing I forgot to ask about...

What is the default receive buffer size of the ROM bootloader? Is it safe to assume that the default values are those that appear in bl_config.h of the example projects (boot_serial)? I am talking about the value that corresponds to the keyword BUFFER_SIZE in bl_config.h

Cheers,
Bryan

Hello Bryan,

And an additional resource that you may find useful.

e2e.ti.com/.../471520

Regards
Amit

Hello Amit,

Thanks for that thread, I read it earlier and it was very helpful. I am writing some code to allow a program to be flashed to the uC using a FTDI USB to UART cable, so my application differs slightly from using another development board as the device programmer

Cheers,
Bryan

Hello Bryan,

The buffer must not exceed 256 bytes (as far as I remember).

Regards
Amit

Hello Amit,

Below is an excerpt from the bl_config.h file from the boot_serial example project:

//*****************************************************************************
//
// The number of words in the data buffer used for receiving packets.  This
// value must be at least 3.  If using auto-baud on the UART, this must be at
// least 20.  The maximum usable value is 65 (larger values will result in
// unused space in the buffer).
//
// Depends on: None
// Exclusive of: None
// Requires: None
//
//*****************************************************************************
#define BUFFER_SIZE             20

Does this mean by default we should always use less than the maximum or just use 20 as per the example project? Or does the ROM bootloader have a larger buffer for receiving packets?

Regards,

Bryan