Nrf52840 UART device compatibility

RE: Nrf52840 UART device compatibility

Simonr — Mon, 09 Dec 2019 13:44:03 GMT

Then it's very hard for me to confirm that they are actually compatible with one another... And for you to know what voltages, baud rates, etc. it supports. It might be that they just don't support each other, and without the correct datasheet, I don't know how to support you any further.

Best regards,

Simon

RE: Nrf52840 UART device compatibility

ephimee — Mon, 09 Dec 2019 09:59:21 GMT

I tried the example, but I don't get any output in the output window?

I don't have a datasheet for the HM-19

RE: Nrf52840 UART device compatibility

Simonr — Fri, 06 Dec 2019 12:48:54 GMT

Hi Philip

That might be the case, but it is strange that the communication works with the FTDI if there are any software issues on the nRF side. You can try using the regular UART example
\<SDK-FOLDER>\examples\peripheral\uart to communicate between the HM-19 and the nRF as well, as that is a very straight forward example that should make it work. Remember to set the baud rate to 9600 if that's what you want though, as the SDK examples are set to 115200 by default.

Are you able to provide the datasheet for your HM-19 so I can take a look at it? I haven't been able to find the datasheet for the correct one I think.

Best regards,

Simon

RE: Nrf52840 UART device compatibility

ephimee — Fri, 06 Dec 2019 08:39:35 GMT

I don't have a logic analyzer.

On the DSD TECH HM-19 it's written 3.6 .. 6V which means it should work with 3.6V but also 5V.

I also just tried to connect the DSD TECH HM-19 to a Arduino Uno, and that is also working fine.
The Arduino Uno is 5V logic.

I also have a Wemos D1 Mini with a ESP8266, which is running on 3.3v.
I tried connecting this as well and it's working fine with the DSD TECH HM-19.

Then I also tried connecting the FTDI to the DSD TECH HM-19, but this time I set the jumper to 3.3v. And also that is working fine.

So I think maybe the problem is in the software settings on the NRF?
I'm pretty new to Nordic, so I could've easily overlooked things?

RE: Nrf52840 UART device compatibility

Simonr — Fri, 06 Dec 2019 07:32:36 GMT

Hi Philip

If the HM-19 is set to 3.6V it should be sufficient to set the DK in normal operating mode, powering it from J2 and having the power select switch set to VDD. Please check if you have any luck here, or else I'm not quite sure on what to look at next. I still suggest trying with a logic analyzer to see what's going on on the TX/RX lines themselves. Are there any differences in how the FTDI and HM-19 transmit and receive?

Best regards,

Simon

RE: Nrf52840 UART device compatibility

ephimee — Thu, 05 Dec 2019 08:27:42 GMT

No, I was using J2 USB originally.

I just tried using the J3 and set the switch to USB power source. So basically I'm now using both J2 and J3 USB ports.
The result is the same. FTDI works fine with the DK, but the DK is unable to communicate with the DSD TECH HM-19.

I haven't tried LLC yet. Which pin on the DK is 3.6V I can use?

RE: Nrf52840 UART device compatibility

Simonr — Thu, 05 Dec 2019 08:01:34 GMT

Hi Philip

Sorry, I didn't realize you were using the DK. You're powering the board using the 5V pin and not the USB connector, right? Now, this pin does allow an input of 5V, but it will not power the nRF with 5V, but rather 3.3V (VDD mode). This might cause some conflicts when communicating with boards that run on higher voltages, so I suggest you power the board in VDDH mode instead to see if that solves the issue. You can power the DK in VDDH mode by either using the USB connector (J3) and setting the power source switch to USB source, or by through the Li-Po battery connectors (J6 or P27) and setting the power source switch to Li-Po.

Alternatively, you can try powering the HM-19 board with 3.6V instead to avoid voltage level conflicts between it and the nRF52840 in VDD mode. Did you have any luck using a logic analyzer to see exactly what happens on the TX/RX lines?

Best regards,

Simon

RE: Nrf52840 UART device compatibility

ephimee — Wed, 04 Dec 2019 14:23:10 GMT

I'm using the nRF52840-DK with the PCA10056, so I was referring to this PCB.

There's nothing else to share, I already provided all the details above.

There's a switch on the board to swap between Li-Po, VDD and USB. But only VDD is working.

RE: Nrf52840 UART device compatibility

Simonr — Wed, 04 Dec 2019 14:15:43 GMT

Hi Philip

Would you mind sharing the schematics of your nRF PCB so I could take a look at your setup? I can set the case to private mode if you don't want to share the schematics with the community. In private mode, your case will be treated confidentially, and only yourself and Nordic engineers will be able to see it.

You can read up on normal (VDD) and high (VDDH) voltage mode in the product specification. Specifically section 5.3.

Best regards,

Simon

RE: Nrf52840 UART device compatibility

ephimee — Wed, 04 Dec 2019 09:35:12 GMT

I'm using the DSD TECH HM-19, which is rated 3.6 .. 6v.

I think it has a built in LLC.

I'm not familiar with VDDH? 5V is written on the P13 header on the NRF PCB so I assumed that the I/O is also 5V?

RE: Nrf52840 UART device compatibility

Simonr — Wed, 04 Dec 2019 09:26:08 GMT

Hi Philip

I wasn't able to find any official voltage parameters for the HM-19 module, but these product specifications indicate that the maximum input voltage to the HM-19 modules is 3.7V. Could the issue be that you're supplying the module with too high of a voltage, and that is what's causing issues? Also, is the nRF52840 set to VDDH mode, so that it supports 5V as well?

You can use a logic analyzer to check what happens on the TX and RX lines to see if there is any activity at all.

Best regards,

Simon