libuarte: Connection between NRF9160dk and NRF52840

[Brett]

Hi,

If there is already a FAQ, Code or support ticket that I missed, I am more than happy to read it.  I have done a number of searches but cant quite get to what I am looking for.

Setup:
I am trying to get communications between the52840 and 9160 on the 9160DK, using libuarte.  I am using zephyr on the 9160 side an the  nrf-sdk on the 52840 side (as I need ANT+).

A few articles I read were using uart1 for this type of communications, so I cut/paste what was in there.  From what I could gather, a way to do this was to use the MCU_IF with pins 17/18 (9160) => 17/20 (52840)

9160 (.overlay file):

&uart1 {

compatible = "nordic,nrf-uarte";

status = "okay";

current-speed = <115200>;

hw-flow-control;

rx-pin = <17>; /* <&interface_to_nrf52840 0 0>; */

tx-pin = <18>; /* <&interface_to_nrf52840 1 0>; */

cts-pin = <19>; /* <&interface_to_nrf52840 2 0>; */

rts-pin = <21>; /* <&interface_to_nrf52840 3 0>; */

};

9160 (main.c)

Device binding is to UART_1:

struct device *uart = device_get_binding("UART_1");

52840 (main.c)

nrf_libuarte_async_config_t nrf_libuarte_async_config = {
        .tx_pin = 17,
        .rx_pin = 20,
        .baudrate = NRF_UARTE_BAUDRATE_115200,
        .parity = NRF_UARTE_PARITY_EXCLUDED,
        .hwfc = NRF_UARTE_HWFC_DISABLED,
        .timeout_us = 100,
        .int_prio = APP_IRQ_PRIORITY_LOW};

Question:

I can get all of this to work (or appears to) when I;
* start the 9160
* move sw to nRF52
* build->debug from SES
 -> click the green run button

* This appears to do everything correctly, receives ANT+, transmits from 52840 to 9160 and I can see it display on the 9160 tty port (using screen).

If I do it any other way, its as if the code on the 52840 is not running, or there is a problem with the connection or a timing issue ?

I added a nrf_delay_ms(5000) at the start of the 52840 code, just in case there was a timing issue between the 9160 and 52840 in that the UART was not ready - but that didnt work.

What am I missing here ?
I feel I have done every possible combination of switches, power and reset, but the only way I can get it to work is if I use SES Build->Debug 

thanks in advance

-brett

[Vidar Berg]

Hi Brett,

On the 52840 side, could you try to call sd_clock_hfclk_request() after enabling the Softdevice? This will make the Softdevice keep the HF crystal oscillator (HFXO) on and in turn increase the accuracy of the UART baudrate generator (it runs off the less accurate HFINT clock by default). I think it's worth trying since you seem to get more stable performance when you keep the chip in debug mode.

I will try to see if I can replicate it here if the above doesn't help.

Best regards,

Vidar

[Brett]

Hi Vidar,

No difference.  It still works in debug mode but fails otherwise.

-brett

[Vidar Berg]

OK, thanks for confirming. I've set up a simple loopback test here now with libuarte running on the 52840 and the Zephyr async driver on the nRF9160 and that seems to work fine. Could you try these 2 projects on your end and see if it works for you as well? Maybe you can spot what we're doing differently.

uart_com_test_52840_9160.zip

-Vidar

Edit: This example selected the wrong UARTE instance. Use the updated projects I uploaded here https://devzone.nordicsemi.com/f/nordic-q-a/79351/libuarte-connection-between-nrf9160dk-and-nrf52840/330790#330790 instead.

[Brett]

Hi Vidar,

I compiled you code (west build -c -p -b nrf9160dk_nrf9160ns), which worked fine and the flash went fine, but on the 9160 I get the following error.

BTW: The 52840 complied and loaded fine.

*** Booting Zephyr OS build v2.6.0-rc1-ncs1 ***
Flash regions Domain Permissions
00 01 0x00000 0x10000 Secure rwxl
02 31 0x10000 0x100000 Non-Secure rwxl

Non-secure callable region 0 placed in flash region 1 with size 32.

SRAM region Domain Permissions
00 07 0x00000 0x10000 Secure rwxl
08 31 0x10000 0x40000 Non-Secure rwxl

Peripheral Domain Status
00 NRF_P0 Non-Secure OK
01 NRF_CLOCK Non-Secure OK
02 NRF_RTC0 Non-Secure OK
03 NRF_RTC1 Non-Secure OK
04 NRF_NVMC Non-Secure OK
05 NRF_UARTE1 Non-Secure OK
06 NRF_UARTE2 Secure SKIP
07 NRF_TWIM2 Non-Secure OK
08 NRF_SPIM3 Non-Secure OK
09 NRF_TIMER0 Non-Secure OK
10 NRF_TIMER1 Non-Secure OK
11 NRF_TIMER2 Non-Secure OK
12 NRF_SAADC Non-Secure OK
13 NRF_PWM0 Non-Secure OK
14 NRF_PWM1 Non-Secure OK
15 NRF_PWM2 Non-Secure OK
16 NRF_PWM3 Non-Secure OK
17 NRF_WDT Non-Secure OK
18 NRF_IPC Non-Secure OK
19 NRF_VMC Non-Secure OK
20 NRF_FPU Non-Secure OK
21 NRF_EGU1 Non-Secure OK
22 NRF_EGU2 Non-Secure OK
23 NRF_DPPIC Non-Secure OK
24 NRF_REGULATORS Non-Secure OK
25 NRF_PDM Non-Secure OK
26 NRF_I2S Non-Secure OK
27 NRF_GPIOTE1 Non-Secure OK

SPM: NS image at 0x10000
SPM: NS MSP at 0x20010a80
SPM: NS reset vector at 0x11885
SPM: prepare to jump to Non-Secure image.
*** Booting Zephyr OS build v2.6.0-rc1-ncs1 ***
uart_init() failed. (err: -6)

cheers

-brett

[Vidar Berg]

Hi Brett,

Can you try to build for "nrf9160dk_nrf9160" instead? Seems like the UART instance I selected won't initialize in the non-secure domain for some reason.  

Cheers

Vidar

Update: I had forgotten to include an overlay file for nrf9160dk_nrf9160_ns so that's why it didn't work. To fix this you can make a copy of the nrf9160dk_nrf9160.overlay file in "boards" and and name it nrf9160dk_nrf9160_ns.overlay.