On Windows, after calling sd_rpc_conn_reset(SYS_RESET) and sd_rpc_close, sd_rpc_open always fails

[Paul Bradford]

I have a nRF52840 dongle (from Fanstel) that is set up as a virtual COM port on my Windows 7 machine, and which I am accessing using pc-ble-driver.

I want to be able to programatically reset my nRF52840.  The only function I see to do this is sd_rpc_conn_reset, which I call with the SYS_RESET option.  I call sd_rpc_conn_reset, and on my Windows 7 system, the virtual COM port for the nRF52840 gets errors (as expected, since the device is resetting), I see a USB device removal for the device, followed a second later by a USB device arrival. At this point the virtual COM port again exists in Windows. But if I try to open that virtual COM port, the file-open operation gets "The system cannot find the file specified" (which causes sd_rpc_open to given the error NRF_ERROR_SD_RPC_H5_TRANSPORT_STATE).   I've tried inserting a delay between when I get the USB device arrival and when I try to open the COM port (to be sure it's ready) but even a 10 second delay still results in the same error.

How can I programatically reset the nRF52840 and then access it again afterwards in Windows 7 using pc-ble-driver?

Thanks,

-Paul Bradford

[bjorn-spockeli]

HI Paul, 

There should be a System Reset command in the Serialization codec, see https://github.com/NordicSemiconductor/pc-ble-driver/blob/master/src/sd_api_v6/sdk/components/serialization/application/codecs/common/conn_systemreset_app.c. 

Best regards

Bjørn

[Paul Bradford]

Let me tell you what I'm trying to accomplish, perhaps that will help.   I'm working on an application that runs on Windows and Linux that uses pc-ble-driver to talk to an nRF52840 dongle. This application needs to be available continuously over long periods of time. The nRF52840 dongle will be plugged into computers that may be in locked cabinets (in hospitals) so we can't ask the user to unplug/replug if the dongle fails for any reason. Therefore I want an nRF52840 software reset that is as close to power off/power on as I can get.   What is my best option?

Is the System Reset command that you're talking about different from sd_rpc_conn_reset ? I saw minimal documentation and no sample of how to call it.

[bjorn-spockeli]

HI Paul, 

 the conn_systemreset_enc() API is an internal one used by the serialization codec. sd_rpc_conn_reset is the correct command to perform a SoftReset of the NRF52840. 

Paul Bradford said:

Therefore I want an nRF52840 software reset that is as close to power off/power on as I can get.   What is my best option?

 The SoftReset will reset the modules listed in the Reset behavior table in the nRF52840 Product Specification. If you want a pin reset, then you will have to add a custom command that can be sent to the nRF52840 over the serial interface that pulls a GPIO that is connected to the RESET pin low. This is what we do with the NRF52840 Dongle when resetting it in bootloader mode, see DFU Trigger Library (USB) .

Best regards

Bjørn