MSPM0L1306: Modify CTL0 SPI register value

Alex Luaces

Part Number: MSPM0L1306
Other Parts Discussed in Thread: TRF7960A, , SYSCONFIG

Tool/software:

Hello, I am making a firmware for a MSPM0L1306 which controls a TRF7960A RFID reader. According to TRF7960A datasheet, when you are sending an instruction to the reader via SPI, it must be done with phase 1 (capturing data on the second clock edge), but when reading, it must be done with phase 0 (on the first clock edge). Please correct me if I am wrong.

I have been analyzing example code for MSP430 MCU, and in the SPI reading function, you can see how the phase is changed with a simple instruction (UCB0CTL0 &= ~UCCKPH; and UCB0CTL0 |= UCCKPH;).

How can I do this with MSPM0L1306? Is there any example code for TRF7960A with a MSPM0 MCU?

5 months ago

0 Diego Abad Sajamin 5 months ago

TI__Genius 14912 points

Hi Alex,
You should be able to modify the phase in SYSCONFIG under the Basic Configuration section.

Best Regards,

Diego Abad

0 Alex Luaces 5 months ago in reply to Diego Abad Sajamin

Prodigy 50 points

Hi and thanks for answering, I used sysconfig to configure it in phase 1, but I need to change it to phase 0 in the course of the program and then change it back.

+1 Diego Abad Sajamin 5 months ago in reply to Alex Luaces

TI__Genius 14912 points

Hi Alex,
You can do this by either changing the SPH bit in the CTL0 register or by creating a new DL_SPI_Config object with the changed .frameFormat set to the desired phase (DL_SPI_FRAME_FORMAT_MOTO4_POL0_PHA0 for 1st or DL_SPI_FRAME_FORMAT_MOTO4_POL0_PHA1 for 2nd) and using it inside the DL_SPI_init function. You can find how Sysconfig sets this through Driverlib inside the ti_msp_dl_config.c file inside the Debug folder of the project.

Best Regards,

Diego Abad

0 Alex Luaces 5 months ago in reply to Diego Abad Sajamin

Prodigy 50 points

Hi Diego, thanks a lot for your answer, I will do it and let you know.

0 Bruce McKenney 5 months ago in reply to Alex Luaces

Guru 99265 points

Some things to note:

1) CTL0:SPH is defined opposite to UCCKPH (so reverse the usage)

2) If you're using the built-in Chip Selects, SPH has an effect on CS for "continuous back-to-back" operations [Ref TRM (SLAU847D) Sec 20.2.3.1]. If you're using a GPIO for CS, this doesn't affect you.

0 Alex Luaces 5 months ago in reply to Bruce McKenney

Prodigy 50 points

Hello, thanks for the hints. I found out that to change the SPH value, I had to disable SPI first, because when I changed its value without disabling it, nothing happened. Is there a way to change it without disabling SPI first?

0 Diego Abad Sajamin 5 months ago in reply to Alex Luaces

TI__Genius 14912 points

Hi Alex,
You are correct. Every time you change a configuration value inside a module, you need to disable it first, and enable it again.

Best Regards,

Diego Abad

0 Alex Luaces 5 months ago in reply to Diego Abad Sajamin

Prodigy 50 points

Hello Diego. If I configure the pins that act as MISO and MOSI with internal pull-down resistors, with they stay low when I disable SPI? In fact, will CCS let me configure them outside the SPI function?

0 Bruce McKenney 5 months ago in reply to Alex Luaces

Guru 99265 points

Maybe you will have to disable/enable around the setting. I noticed some months ago that changing FRF required this (though that seems more drastic than changing SPH). Yesterday I skimmed the TRM and the strongest statement I found was [TRM Sec 20.2.5 Step (1) "Ensure.."]. But maybe it's true anyway.

You may find that the disable/enable are benign; the IOMUX will hold the pin signals steady while the peripheral is disabled [Ref TRM Sec 9.2.1].

+1 Bruce McKenney 5 months ago in reply to Alex Luaces

Guru 99265 points

The internal pull-ups/-downs are managed by the IOMUX, independent of the peripheral. So yes, they will stay engaged. [Ref TRM Sec 9.2.5]

[Edit: Added reference]

0 Alex Luaces 5 months ago in reply to Bruce McKenney

Prodigy 50 points

Hi Bruce, thank you very much!

0 Diego Abad Sajamin 5 months ago in reply to Alex Luaces

TI__Genius 14912 points

Hi Alex,
I'm glad Bruce's comment helped you. If you need further help, you can ask it here. However, if it is not closely related to this original question, I would recommend creating a new E2E thread.
Best Regards,
Diego Abad

0 Alex Luaces 5 months ago in reply to Diego Abad Sajamin

Prodigy 50 points

Thanks Diego, in case of need, I will.

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MSPM0L1306: Modify CTL0 SPI register value