Easy DMA on SPI

[Ashokrajpilli]

1. can you tell in detail about Easy DMA supporting on SPI, I would like to understand how I can utilize DMA feature for communication with RAM over SPI what is the added advantage I can gain when compared with process interacting with RAM. 

2. active tamper shield; how can I enable this feature ? how is it different from external switch ? I assume external switch means a physical switch in the hardware that needs to be connected to one GPIO to detect the opening of any enclosure/lid/plastic housing. Can you specify any application notes that uses and emphasis the delta between active tamper shield pin pairs and external switch ?

[Einar Thorsrud]

Hi,

1. can you tell in detail about Easy DMA supporting on SPI, I would like to understand how I can utilize DMA feature for communication with RAM over SPI what is the added advantage I can gain when compared with process interacting with RAM. 

There is no option to not use DMA with the SPI peripherals in the nRF52L15 (older nRF52 series devices had legacy peripherals without DMA as well as peripherals with DMA). So any SPI transaction will use DMA, and a bufffer and buffer size is provided for Tx and Rx before the start of the transaction. During the transcting it is handled in HW and requiers no CPU. Note that the low-level parts are handled by the driver, so this normally does not requier any special consideration.

2. active tamper shield; how can I enable this feature ? how is it different from external switch ? I assume external switch means a physical switch in the hardware that needs to be connected to one GPIO to detect the opening of any enclosure/lid/plastic housing. Can you specify any application notes that uses and emphasis the delta between active tamper shield pin pairs and external switch ?

A switch is simpler and can more easily be buypasse by a carefull atacker. The active shield works by connecting the shield from an output pin to an input pin on the TAMPC, and this send a pseudo ransom signal and compares the input signal with the outptu signal. If the signals differ, that indicate someone is tampering with the shield. See Active shield in the TAMPC section in the datasheet for details.