Upgrading BLE firmware through DFU over uarthttps://devzone.nordicsemi.com/f/nordic-q-a/4519/upgrading-ble-firmware-through-dfu-over-uartHello, I am working on nrf51822, My requirement is to upgrade the firmware over the uart with help of DFU. I have made code for that on controller side and fortunately I am able to upgrade the image. But when i restart the chip and again try toen-USTelligent Community 13Tue, 14 Apr 2015 11:23:24 GMTRE: Upgrading BLE firmware through DFU over uarthttps://devzone.nordicsemi.com/thread/16034?ContentTypeID=1Tue, 14 Apr 2015 11:23:24 GMT137ad170-7792-4731-bb38-c0d22fbe4515:ec03cc59-314f-437f-b92f-be25669f775fdc<p>I am not able to update firmware using serial UART. I have used SDK 6.1.0</p> <p>I am getting following error all time Progress:0 Transmission Timeout Ack out of sequence or no ack returned.</p><div style="clear:both;"></div>RE: Upgrading BLE firmware through DFU over uarthttps://devzone.nordicsemi.com/thread/16032?ContentTypeID=1Tue, 14 Apr 2015 11:23:16 GMT137ad170-7792-4731-bb38-c0d22fbe4515:5d6f7b07-54cd-4c3e-bd4e-218d2256fd75dc<p>I am not able to update firmware using serial UART. I have used SDK 6.1.0</p> <p>I am getting following error all time Progress:0 Transmission Timeout Ack out of sequence or no ack returned.</p><div style="clear:both;"></div>RE: Upgrading BLE firmware through DFU over uarthttps://devzone.nordicsemi.com/thread/16033?ContentTypeID=1Fri, 21 Nov 2014 04:34:13 GMT137ad170-7792-4731-bb38-c0d22fbe4515:bb574393-a77d-4765-8a08-9e837a7db942Hardik<p>I got the solution. the second time when we are sending start packet , sometimes its not acknowledging back so we have to keep sending until its start acknowledging.</p> <p>I made the changes accordingly in my code and now its working fine.</p> <p>Thanks</p> <p>Regards, Hardik</p><div style="clear:both;"></div>