DATA FILE TRANSFER FROM SD CARD TO MOBILE USING USB PROTOCOL. HOW TO DO IT IN NRF52840

[jagannathan GOPALAKRISHNAN]

we are using NRF52840 , with a SD card.  Data is stored in SD card in Text file or .csv file every 10 mins.  We want to push the data to Mobile App either using the BLE or using the USB protocol.  Kindly advice .

[Jørgen Holmefjord]

Hi,

I created an example with ble_app_uart that read a specified file on boot and when a central is connected and notifications for NUS are enabled, the file is transferred to the central.

This example is created using SDK v16.0.0. 

ble_app_uart_fatfs_send_sdk_16.0.0.zip

Best regards,
Jørgen

[jagannathan GOPALAKRISHNAN]

Thanks Mr. Jorgen.  It worked. I need one more help. I want to connect the USB to a device other than Computer.  We are using the STM32bit controller. can u suggest.  

[Turbo J]

Does the STM32 support USB host mode (or OTG)? You need this in order to be able to connect to an NRF chip, as these can only be in USB device role.

If the STM32 cannot be USB Host, you are probably better off connecting these chips via SPI.

[Samiulhaq]

Hey Jorgen, thanks for the example. I have a large file of 240MB on an SD card and I want to transfer this file to the mobile app at once not byte by byte just like you have done in the above example. The byte by byte transfer will take a lot of time as the file size is large and also controlling it on the app side will be difficult. So, I want to transfer my file to the App at once. Can you please recommend to me the fastest possible to do it, 

Thanks & best regards,

Sami 

[Jørgen Holmefjord]

Hi,

It is not possible to send 240 MB over BLE in one go, you will have to divide the file into smaller chunks that can fit inside the BLE packets.

Best regards,
Jørgen