nRF52832 SPI Slave clock frequency.

RE: nRF52832 SPI Slave clock frequency.

awneil — Thu, 26 Mar 2020 10:03:49 GMT

[quote userid="86435" url="~/f/nordic-q-a/59477/nrf52832-spi-slave-clock-frequency/241694"]Do you know the nRF52832's maximum frequency[/quote]

As always, that will be in the datasheet (aka "Product Specification"):

https://infocenter.nordicsemi.com/index.jsp?topic=%2Fstruct_nrf52%2Fstruct%2Fnrf52832.html&cp=3_2

EDIT

I'll try that link again:

https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/spis.html?cp=4_2_0_31_5#unique_631156952

RE: nRF52832 SPI Slave clock frequency.

awneil — Thu, 26 Mar 2020 09:59:55 GMT

[quote userid="86435" url="~/f/nordic-q-a/59477/nrf52832-spi-slave-clock-frequency/241694"]SPI Master has confirmed normal operation at 4Mhz and 8Mhz[/quote]

How, exactly, has that been confirmed?

[quote userid="65515" url="~/f/nordic-q-a/59477/nrf52832-spi-slave-clock-frequency/241696"]The problem is the drive strength of the output pins, methinks[/quote]

Note that the STM32 also has settings for this - so check there also.

[quote userid="65515" url="~/f/nordic-q-a/59477/nrf52832-spi-slave-clock-frequency/241696"]CS, SCK and MOSI pins which are output from the nRF52[/quote]

No: the nRF is Slave here - so those are all inputs.

MISO is an output on the Slave.

Chikyoung - have you looked at the wires with an oscilloscope - that should show you if you have drive strength problems ...

RE: nRF52832 SPI Slave clock frequency.

hmolesworth — Thu, 26 Mar 2020 00:40:19 GMT

The problem is the drive strength of the output pins, methinks. Try this:

//Edit: I misread the original post aw awneil points out; these are inputs
//      but need to be set to high-Drive on the ST
 nrf_gpio_cfg(APP_SPI0_CS_PIN,  NRF_GPIO_PIN_DIR_OUTPUT, NRF_GPIO_PIN_INPUT_DISCONNECT, NRF_GPIO_PIN_NOPULL, NRF_GPIO_PIN_H0H1, NRF_GPIO_PIN_NOSENSE);
 nrf_gpio_cfg(APP_SPI_MOSI_PIN, NRF_GPIO_PIN_DIR_OUTPUT, NRF_GPIO_PIN_INPUT_DISCONNECT, NRF_GPIO_PIN_NOPULL, NRF_GPIO_PIN_H0H1, NRF_GPIO_PIN_NOSENSE);
 nrf_gpio_cfg(APP_SPI_SCK_PIN,  NRF_GPIO_PIN_DIR_OUTPUT, NRF_GPIO_PIN_INPUT_DISCONNECT, NRF_GPIO_PIN_NOPULL, NRF_GPIO_PIN_H0H1, NRF_GPIO_PIN_NOSENSE);

So just this on the nRF52: 
 nrf_gpio_cfg(APP_SPI_MISO_PIN,  NRF_GPIO_PIN_DIR_OUTPUT, NRF_GPIO_PIN_INPUT_DISCONNECT, NRF_GPIO_PIN_NOPULL, NRF_GPIO_PIN_H0H1, NRF_GPIO_PIN_NOSENSE);

or the equivalent in whatever IDE you are using; the idea is High Drive '1' and '0' for CS, SCK and MOSI pins which are output from the ST and MISO which is output from the nRF52 in order to get 4MHz, 8MHz or even 16MHz operation. This must be done after the SPI initialisation, not before.

RE: nRF52832 SPI Slave clock frequency.

Chikyoung — Thu, 26 Mar 2020 00:31:04 GMT

Thank you for your reply.

I mean there are issues with communications when the frequency is set higher.

SPI Master has confirmed normal operation at 4Mhz and 8Mhz.

However, It does not work when connected with nRF52832 in 4Mhz and 8Mhz.

It worked fine at 2Mhz.

Do you know the nRF52832's maximum frequency?

RE: nRF52832 SPI Slave clock frequency.

Chikyoung — Thu, 26 Mar 2020 00:22:49 GMT

Thank you for your reply.

Do you know the nRF52832's maximum frequency?

RE: nRF52832 SPI Slave clock frequency.

awneil — Wed, 25 Mar 2020 10:46:31 GMT

[quote userid="14926" url="~/f/nordic-q-a/59477/nrf52832-spi-slave-clock-frequency/241559"]There is no frequency config on the nRF side for the SPIS peripheral, it will run at whatever frequency the SPI master uses[/quote]

Indeed.

That's the whole point of a synchronous link like SPI: the same would apply to any slave - not specific to nRF.

(other that the physical limit on the maximum frequency of the slave's hardware).

Of course, the faster the data is going, the more careful you have to be with your slave code to ensure that it has the capacity to handle the data ...

RE: nRF52832 SPI Slave clock frequency.

Jørgen Holmefjord — Wed, 25 Mar 2020 10:36:55 GMT

Hi,

There is no frequency config on the nRF side for the SPIS peripheral, it will run at whatever frequency the SPI master uses, within the SPIS electrical specifications.

[quote user=""]normal communication with nRF52832 operates only at 2Mhz[/quote]

What exactly do you mean by this? Do the master not generate a clock faster than 2 MHz, or are there some issues with the communications when the frequency is set higher?

Best regards,
Jørgen

RE: nRF52832 SPI Slave clock frequency.

awneil — Wed, 25 Mar 2020 08:42:10 GMT