How to use PTB0 instead of SDA interface on s32k116 EVB

[NicoloStrozzi]

Hello,

I need to use PTB0 as SPI_CS instead of UART_RX for Open SDA interface on S32K116 EVB (S32K116EVB2Q048). 

I'm currently programming the board using PE micro Universal Multilink FX debugger and everything works fine, but when I try to use PTB0 from header J3-2 of the board I'm not able to use it. Means that when I set this pin as Chip Select for SPI, and I try to send a message, I'm expecting that the logic value on PTB0 fall from 1 to 0 (CS active low) but instead it remains high.

Seems that the UART_RX control from OpenSDA interface is still taking control of this pin even if only external debugger is connected to SWD header and USB cable is detached.

[Robin_Shen · Accepted solution]

Hi

My S32K116EVB2Q048 is the SCH-47484 REV A version. J107 connects 1-2 to use P5V_SBC for power supply. Power the board with external 12V at J16 without debugger. At this time, I am able to see the waveform of SPI0_PCS0 on PTB0.
I measured the PTB0 signal through J3.2, and the R754 on the bottom of the board is soldered.
The tested project only changed the PCS pin of lpspi_dma_master_s32k116_SDK403 from PTB5 to PTB0.

Best Regards,
Robin
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[NicoloStrozzi]

Hi,

thank you for your suggestion, now the PTB0 is available for SPI_CS use. In order to test PTB0 and PTB1 USB must be detached. This means that I need to supply the MCU by SWD (J14-1) or VBAT. I was not been able to do it because J15 jumper was not connected and I was not understanding that it is not only for MCU current measurement purpose.

In the EVB schematic is not stated that VDD_MCU is connected to J107-2. So if you need to provide power supply to MCU by SWD (J14) you need to connect J15. If you need to provide power supply through VBAT you need to connect J15 and J107 (1-2). If you want to provide power supply through USB, J15 could be detached but J107 need to be connected on 2-3.

Am I right?

[Robin_Shen]

Sorry I didn't understand your question.
J15 is connected by default, which is used to power VDD_MCU. If you want to measure current, just disconnect J15 and connect an ammeter in series to measure the current. Whether you want to use USB (J7) or 12V (J16) to power the development board, J15 needs to be connected so that VDD_MCU can get energy.

Or can you modify the hardware circuit? By modifying the voltage of SDA_RX_EN, the transmission direction of U4 74LVCH1T45 can also be changed. Or disconnect R24? (This means that you can use USB cable to power the board and also use SPI0_PCS0 PTB0)

[NicoloStrozzi]

I understand that J15 is connected by default (physical bridge is present) but it wasn't clear to me that it's mandatory to mount it in order to provide power supply to MCU.
Moreover there is no reference in the EVB schematic that VDD_MCU is connected J107-2 so it was not clear how VDD_MCU is delivered to MCU when attached to USB (P5V_SDA_PSW is never connected to VDD_MCU or VDDA_MCU, see pictures here below):
I've already modified the HW to completely exclude OpenSDA interface. 
Anyway now my project works fine and I'm able to debug using PE micro debugger while using PTB0 and PTB1 on EVB, thank you.