[SL8082][XMODEM] Padding last packet during update

Legacy Legacy AirPrime modules
1

Hello,

I’m writing some application which is going to update my SL8082 module through XMODEM protocol. The thing is that my application file isn’t multiply of the 1kB or 128B, it means that last packet must be padded somehow. According to the specification of XMODEM-1k which I found last packet shall be padded with control sign which is 0x1A. However when I’m padding my last packet with it, then sending and trying to restart with AT+CFUN=1 I got following error:

<CAN><CAN><CR><LF>***ERROR***<CR><LF>AT+CFUN=

Contrarily, when I’m padding last packet with it means 0x00, everything is OK. Could tell me what is the reason of following behavior ? Does somebody choose as padding sign ignorred by SL8082 module ? I’ve tried padding with 0xFF like in my opinion clean flash memory should be initialized. I’d be greatefull for somekind of documentation to the XMODEM-1k implementation used on this chip. I’ve found only following reference till this time:

http://mycusthelp.net/SIERRAWIRELESS/_cs/AnswerDetail.aspx?sSessionID=&aid=487

2

Hi babula,

To my understanding, padding with 0x1A is coming from Xmodem spec and works on SL8, have you got ACK response before you send the EOT?

Thx

3

Hi,

exactly padding with 0x1A comes from XMODEM specification, but modem returns NACK when it receives padding of 0x1A.