Error in ISP of LPC812: Lost characters when sending bytes too fast to LPC812 with command 'W'

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by capiman on Fri Jun 28 04:38:12 MST 2013

I use ISP to program a LPC812. Baudrate is 115200. Echo in ISP is on.

According to user manual no XON/XOFF is used and also no other flow control. Also i have not seen a baudrate limit for ISP.

I send a command 'W' with length 1024. Then i send 1024 bytes of data in one go (WriteFile from Windows over FTDI 2.8.28).

The number of echoed characters is sometimes less than 1024 (e.g. 1020). When looking into the received data stream and comparing the data with the sent data, i see that some bytes are missing. There a different bytes missing, so i assume it is not because of the content of the data.

What is perhaps interesting, is, that the time the LPC812 needs to answer on a received byte, seems to be increasing. Why? Some time, when the time is too big, a character gets lost, so time is reduced, till the time is small enough again. It starts with 100 us, and when error occurs the delay by LPC812 is already up to a value of 326 us...

When i reduce the number of bytes to 4 x 256 bytes, it seems the error does not occur, or at least rate of occurance is reduced.

(this gives LPC812 time to get breath again)

BTW: I use a LPCXpresso with LPC812 on it, bootloader version 13.1