nrf21540 interface to 528xx

RE: nrf21540 interface to 528xx

user108933 — Thu, 12 May 2022 09:35:34 GMT

Hello Jorgen,

1. When you say you can't change gain "dynamically", I assume you you referring to the changing gain on 21540 during runtime of an application?

yes

2. If I stop application I should be able to change Gain parameter on 21540, right? I.e I don't have to reset the device, right?

It would be possible , you need to reset the device.

3. If I set a "fix gain" on 21540 to achieve total of +19dbm I assume I can dynamically reduce output power on 52840, through the 52840 USB port, right?

You can change the tx power on the nRF52, you can see this https://github.com/nrfconnect/sdk-zephyr/tree/main/samples/bluetooth/hci_pwr_ctrl samples of hci_pwr_control where dynamic Tx power controls over the LL of the BLE controller via Zephyr HCI VS command. A peripheral advertises by varying the TX power. The initial TX power is the default power set for the application in Kconfig. Later the TX power variation of the peripheral device varies from -4dBm to -30dBm where the power level decreases every 5s. However , we do not have any sample that does this through USB.

There is a sample https://github.com/nrfconnect/sdk-zephyr/tree/main/samples/subsys/usb/cdc_acm which demonstrates use of a USB communication Device Class (CDC) Abstract Control Model (ACM), received data from the serial port the serial port is echoed back to the same port provided by this driver.

It should be possible to combine so that you can send commands though USB.

Thanks.

Best Regards,

Kazi Afroza Sultana

RE: nrf21540 interface to 528xx

user114890 — Fri, 06 May 2022 22:38:11 GMT

Thanks Kazi for answers.

When you say you can't change gain "dynamically",
I assume you you referring to the changing gain on 21540 during runtime of an application?
If I stop application I should be able to change Gain parameter on 21540, right? I.e I don't have to reset the device, right?
If I set a "fix gain" on 21540 to achieve total of +19dbm I assume I can dynamically reduce output power on 52840, through the 52840 USB port, right?
This is not something "technically feasible" it already works, right?

Sorry if these are fundamental questions. Just want o make sure I don't spend days on trying to make something work if not supported yet.

Thank you!
Jorgen

RE: nrf21540 interface to 528xx

user108933 — Fri, 06 May 2022 14:57:47 GMT

Hello,

You can look at this documentation about working with RF fron End Module https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/ug_radio_fem.html#

2.Are all the drivers for TX and RX signals etc. to 21540 interface are available in the examples and SDK?

yes

3. Can I use K-config in VS to configure 21540 including gain parameter?

yes mostly the device tree is used for this.

4. Is the configuration for the 21540 being written through the 52840 SPI?

yes

5. Can I write the USB port of the 52840 chip to set the gain on 21540 (not using Jlink debugger) and how?

According to our expat in team

It's technical feasible, but we don't have any samples that show-case this, and MPSL is also currently missing features for adjusting output power dynamically.

Thanks.

Best Regards,

Kazi Afroza Sultana

RE: nrf21540 interface to 528xx

user114890 — Thu, 28 Apr 2022 19:06:47 GMT

Yes, eval board schematics works fine. Didn't realize you had the 21540 chip on the 21540 DB pcb actually.
Are you working on Qestions : 2-5?
(I haven't received 21540 DB I ordered yet)

RE: nrf21540 interface to 528xx

user108933 — Wed, 27 Apr 2022 12:36:14 GMT

Hello Jorgen,

We do not have any schematic that shows interface between nRF21540 with nRF52840. But you can find hardware file of nRF21540 here. nRF21540 DB - Downloads - nordicsemi.com

You need to have all the control lines (e.g. rx, tx, power down etc) and the spi interface connected up to the nRF52840, because the software implementation use both.

Best Regards,

Kazi Afroza Sultana

RE: nrf21540 interface to 528xx

user114890 — Thu, 21 Apr 2022 16:59:11 GMT

Hi Kazi,

I just realize that the development kit nrf21540 DK is the nrf52840DK+nrf21540. This will make it easier to test out.
(I was under impression that I had to plug in the nrf21540 EK to the nrf52840 DK.)

Just to review questions:

Again there is no actual schematic on 21540/52840 interface of the nrf21540DK in the user guide.

1. Can you provide a schematic for this?

I see some application examples for "light bulb" and "light switch" using 21540 and 82540 in Visual Studio Coder.
2.Are all the drivers for TX and RX signals etc. to 21540 interface are available in the examples and SDK?

3. Can I use K-config in VS to configure 21540 including gain parameter?
4. Is the configuration for the 21540 being written through the 52840 SPI or ?
5. Can I write the USB port of the 52840 chip to set the gain on 21540 (not using Jlink debugger) and how?

Thanks again,
Jorgen

RE: nrf21540 interface to 528xx

user114890 — Thu, 21 Apr 2022 13:25:42 GMT

Hello Kazi,

I have seen the schematic in the link you provided.
https://www.nordicsemi.com/Products/nRF21540/Downloads?lang=en#infotabs

This only shows the nrf21540. It does not show a nrf528xx or another SoC connected.
Can I assume the net names in schematic are correct for the nrf52840 and there are no other components on these nets needed on the nrf528xx side?

In regards to SPI interface:
Sorry, just to be a bit more clear.
I assume that any real time control would be with done with GPIO such as for TX and RX etc. since fast switching is needed. So it would be "SPI and GPIO"
However if I want to change gain parameter in real time is there a API command (BDB, or a specific "21540 command") for this I can send to the USB port of nrf52840 which would then be sent to SPI interface to nrf21540 to set gain?

The links you sent to the other tickets are "private" which I can't see.

Thanks,
Jorgen

RE: nrf21540 interface to 528xx

user108933 — Thu, 21 Apr 2022 09:07:20 GMT

Hello,

I'm looking for reference schematic for the interface between nrf52840 (or similar) and the nrf21540 . Is there a simpler version than the developer kit user guide version in 21540 section? Have to trace it all out and can easily miss something.

We have schematic diagram for nrf21540 nRF21540 RF FEM - Downloads - nordicsemi.com.

Also is there some documentation and examples on how to write to nrf528xx USB port (not the usb/jlink on eval board) so I can configure the nrf21540 gain and some other parameters using the spi interface of the nrf52840?

Using only SPI interface interface is not supported, either spi and GPIo or only GPIO. There are some similar devzone post SPI vs IO interface - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com), https://devzone.nordicsemi.com/support-private/support/276829 , https://devzone.nordicsemi.com/support-private/support/282533 you can look at.

Thanks.

Best Regards,

Kazi Afroza Sultana

RE: nrf21540 interface to 528xx

user114890 — Wed, 20 Apr 2022 14:13:41 GMT

Thanks Kazi!
I'm also wondering if Nordic provides all the access to configuration of the nrf21540 in Visual Studio Connect and does all the real time TX and RX operations have examples that can be used so I don't have to figure this out myself?

Can all these configuration be included in config file for nrf52840 and then the nrf52840 configures the nrf21540 on powerup through GPIO serial port etc.? Such as "Tablet 3 MCU to FEM" in 21540 user guide. MCU would be the nrf52840 in this case.
Perhaps this is obvious, but it's not clear what real time functions Nordic provides.
Thank you!

RE: nrf21540 interface to 528xx

user108933 — Wed, 20 Apr 2022 13:26:24 GMT

Hello,

I have started looking at your case. I will get back to you later.

Thanks.

Best Regards,

Kazi Afroza Sultana