52820 LPCOM problem

[zero]

Dear friend
I checked the data sheet of 52820 and I didn't see any LPCOMP peripherals. Check the data sheet of 52832, there are LPCOMP peripherals. Comparing COMP and LPCOMP, the registers are basically the same. It is also found that COMP supports low power mode.

Does 1.52820 support LPCOMP?
2.52820 If configured to low power mode, is the function consistent with LPCOMP?

[Jørgen Holmefjord]

Hi,

There is no LPCOMP peripheral in the nRF52820, only LPCOMP is available. 

The two peripherals is not identical. COMP have more steps on the reference ladder (64 vs 15 for LPCOMP), and more choices of references (including 8 external references, internal reference voltages (1.2, 1.8, and 2.4V), LPCOMP can only use a fraction of VDD as reference, or 2 external reference). COMP also supports differential mode, where you can detect small variances between two input signals.

LPCOMP can on the other hand be used to wake the chip from System OFF sleep mode, this is not possible with the COMP peripheral.

Best regards,
Jørgen

[Jørgen Holmefjord]

zero said:

1. If COMP is set to low power mode, what is the difference with LPCOMP?

Like I said, these are two separate peripherals, with different feature set. COMP will still have the same features, regardless of the configured mode. The mode will affect the propagation delay, causing slower response time. See COMP Electrical Specification for details on this.

zero said:

2. Can COMP be set to low power to wake up the chip?

No, this is a feature of the LPCOMP peripheral only, it is not available from COMP peripheral.

zero said:

3. COMP is set to low power mode. Is the power consumption of COMP consistent with that of LOPCOM?

No, you can compare the current consumption of the two peripherals in the nRF52832 PS chapters COMP Electrical Specification and LPCOMP Electrical Specification.

[zero]

Hi Jørgen,

I added the COMP code on sdk17.0.2 and ran it on 52820, but I saw that the interruption had no effect. Check the nrfx_prs.h file. NRF_COMP is not defined on 52820.

What should I do to use interruption?

Best regards,
Zero

[Jørgen Holmefjord]

Hi,

The peripherals are not defined inside PRS, the PRS (Peripheral Resource Sharing) library is used to manage shared resources in the chip. For the COMP peripheral, this means allowing COMP and LPCOMP to be used from the same application, while preventing both from being initialized at the same time. Since nRF52820 does not include a LPCOMP peripheral, there is no need to add COMP to PRS.

NRF_COMP is defined in nRF5_SDK_17.0.2_d674dde\modules\nrfx\mdk\nrf52820.h:2056.

Can you post the code you used for configuring and initializing the COMP peripheral?

Best regards,
Jørgen