TMS320F28377S: SCI boot mode - GPIO selection for SCIA TX and RX

Paul Hetherington

SCI boot mode (GPIO72 = 0, GPIO84 = 1 during boot)

We'd like to assign SCI_A_RX and SCI_A_TX to GPIOs 28 and 29. SPRS881J indicates that this is possible with the SCI-Boot1 selection. See table 8-14 below. The Technical Reference Manual indicates that BMODE = 0x81 selects SC-Boot1, but describes this as a seletion that applies to the Get boot mode. Table 4-6 below.

Does the BMODE setting also apply to SCI boot mode ?

Thanks in advance.

7 months ago

+1 Allison Nguyen 7 months ago

TI__Mastermind 27050 points

Hi Paul,

The boot mode pins (GPIO72, GPIO84) determine which boot mode selection method is used, while the BMODE field determines the specific boot configuration only when "Get" mode is selected. You cannot use GPIO28/GPIO29 for SCI boot by simply setting GPIO72=0, GPIO84=1 - you must use the "Get" mode approach.

Best Regards,

Allison

0 Paul Hetherington 7 months ago in reply to Allison Nguyen

Intellectual 340 points

Hi Allison,

Follow up questions:

1. To use Get boot mode via SCI-A on GPIOs 28 and 29 we need to set BMODE = 0x81. My understanding is that BMODE is in OTP flash and that this value can only be programmed once. Is this correct?

2. If we dedicated Get boot mode to use SCI-A, is there an alternative way to boot from Flash.

Thanks

Paul Hetherington

0 Allison Nguyen 7 months ago in reply to Paul Hetherington

TI__Mastermind 27050 points

Hi Paul,

Looping in our bootloader expert to help further explain this process.

Best Regards,

Allison

+1 Matt Kukucka 7 months ago in reply to Allison Nguyen

TI__Mastermind 20380 points

Hi Paul,

Apologies for the delay, there was a holiday last week in the US.

Paul Hetherington said:
. To use Get boot mode via SCI-A on GPIOs 28 and 29 we need to set BMODE = 0x81. My understanding is that BMODE is in OTP flash and that this value can only be programmed once. Is this correct?

Yes, that is correct, the OTP can only be programmed once. I will note that you technically have two attempts to program the OTP since there are two zones in the OTP (Z1 and Z1). Z2 boot configurations take precedence over Z1.

Paul Hetherington said:
2. If we dedicated Get boot mode to use SCI-A, is there an alternative way to boot from Flash

Unfortunately, once you assign Get mode to an alternate boot mode (like SCI boot with GPIO28/29), then flash boot is not possible.

Best,

Matt

0 Paul Hetherington 7 months ago in reply to Matt Kukucka

Intellectual 340 points

Thanks very much!

Paul Hetherington

C2000™︎ microcontrollers

C2000 microcontrollers forum

TMS320F28377S: SCI boot mode - GPIO selection for SCIA TX and RX