NTM88_GenFSK_Beacons PTA0 CS not used?

[Markel]

Hi,

I am reviewing the NTM88_GenFSK_Beacons example beacon, and it seems that the PTA0 CS is not being detected at NTM88. Is this correct?

I am going to connect the NTM88 to TI BLE MCU. If the TI BLE MCU pulls the CS line low, the NTM88 would read the sensor data and save to buffer array. I do not need the Wake Up and KBI.

Would my intended functionality work if I read PTA0 before reading the sensors, see code modification below.

Then I just need to comment out the codes below for WAKEUP_PIN_HIGH and waiting for acknowledgment at PTA3/KBI.

Regards,

Markel

[Markel]

Thanks, 

[Markel]

Hi,

What I am saying the PTA0 is not being read at NTM88. Seems like it serves no purpose at the NTM88_GenFSK_Beacons example program.

I intend to connect the NTM88 to TI BLE MCU using SPI interface. The TI BLE MCU needs to be discoverable and connectable. So, I can not have the NTM88 wake it up every 2 seconds. I also have a SPI external flash connected on the SPI bus. After I configure, the TI BLE MCU GPIO's as SPI, I may not be able to re-configure 1 SPI pin to serve as KBI input to NTM88.

Using the PTA0 as KBI interrupt is a good option. But, after I pull the PTA0 low from host MCU, would the NTM88 keep running? It seems how the NTM88 KBI is configured is that, I have to pull the KBI input low every time the host MCU would need to get sensor data from NTM88.

I will check out the example project you shared.

Regards,

Markel

[TomasVaverka · Accepted solution]

Hi Markel,

PTA0 is used as SPI chip select. What do you mean by “not being detected as NTM88”?

No, if KBI is not used it will not work. When the NTM88 is in sleep (either STOP1 or STOP4), the SPI block is disabled. When the NTM88 is in sleep, if KBI is disabled and the host MCU pulls the CS pin low, this will have no effect on the NTM88 (i.e. the NTM88 will not wake up). The only way for the host to wake up the NTM88 from sleep via GPIO is to use the KBI block.

KBI interrupt can be configured on any of the PTA0 to PTA3 pin. So it is possible to use PTA0 as KBI pin instead of PTA3. In that case, the NTM88 would go to sleep with KBI enabled on PTA0. When the host pulls PTA0 line low, the NTM88 would wake up on KBI interrupt. Once the MCU is in RUN, the application can enable SPI so the BLE MCU can read the NTM88 memory.

In the GenFSK Beacons demo, it is the NTM88 that wakes up the BLE host. If the desired implementation is the other way around (i.e. the BLE host wakes up the NTM88), then the demo project “NTM88_BLE_Beacons_mode_8” would be more appropriate as a starting point. This demo project can be found in the package at:

https://www.nxp.com/webapp/Download?colCode=NTM88-KW38-BLE-BEACONS&appType=license

Best regards,

Tomas