52832 twi clk low time ---"tLow" is not clarified in spec

[William.wei]

hi support team,

customer has one question about TWI electricity. in the IIC spec the "tLow " should be more than 1.3 us

however, our chip interface TWI timing " tLow " is not list in spec(49.9.2 Two Wire Interface (TWI) timing specifications) as below

unfortunately, from our errata, that our TWIM seems to be somehow wrong according to such link:

https://infocenter.nordicsemi.com/topic/errata_nRF52832_Rev2/ERR/nRF52832/Rev2/latest/anomaly_832_219.html

so, if our chip meeting this requirement, if yes do we have document about this? if not, what's the workaround(TWI), any consequence?

Regards,

William.

[Håkon Alseth]

Hi,

 

unfortunately, from our errata, that our TWIM seems to be somehow wrong according to such link:

https://infocenter.nordicsemi.com/topic/errata_nRF52832_Rev2/ERR/nRF52832/Rev2/latest/anomaly_832_219.html

In order to be within the "tLow" parameter of 1.3 us, you should implement the workaround as described in erratum #219.

The period of the frequency is 1/f, where period consists of a low period and a high period. By lowering the frequency, you are able to be within the requirement of "tLow" 1.3 us.

 

Kind regards,

Håkon

[William.wei]

thanks Alseth,

that link suggests workaround for TWIM, do you know the FREQUENCY value for TWI?

Regards,

William.

[Håkon Alseth]

Hi William,

 

The baudrate generator is the same on both modules, but do note that TWI is a deprecated peripheral, and that using TWIM is recommended. Are you certain that they use the NRF_TWI, and not the NRF_TWIM? You can verify this by reading the ENABLE register.

If it is '5', its TWI. If it is '6', its TWIM, as per the datasheet:

https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/twi.html#register.ENABLE

https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/twim.html#register.ENABLE

 

Kind regards,

Håkon

[William.wei]

hi Alseth,

i don't understand why TWI is not recommended, i thought it is compatible with 51 serials;

the example is still available under SDK ----"examples\peripheral\twi_master_with_twis_slave", and example still works, we still have customers using TWI not TWIM;

and there is  one chapter about twi in our spec.

Regards,

William.

[Håkon Alseth]

Hi William,

 

On the nRF52-series devices; "TWI" is present and can be used.

As stated in the product specification, a peripheral marked with "deprecated" isn't recommended for new designs:

https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/about.html?cp=4_2_0_1_2_0#fields_values

 

It is present for backwards compatibility reasons, and not present on newer chip families, like nRF91 and nRF53.

 

Kind regards,

Håkon