[Ovmsdev] sprintf / crashes

[Michael Balzer]

Mark,

transparent chunk splitting seems to be non-trivial, so I split my data 
transfers. Everything's working fine again, so I'll merge into the 
master next if you don't object.

Btw, AT+CIPSEND? gave me 1460 bytes, so that's supposed to be the size 
limit we should keep in mind until we find a better solution.

@Nikolay: please note, that's the total size that can be sent within one 
net_msg_start() ... net_msg_send(), the buffer size (net_scratchpad) 
further limits a single MSG line to currently 199 bytes max.

Regards,
Michael


Am 31.12.2012 16:23, schrieb Michael Balzer:
> Mark,
>
> I think I found my link dropping problem: scanning a diag log I took, 
> I found out CIPSEND will fail with a plain "ERROR" if the data size 
> exceeds about 1500 bytes. I guess that's either the SIM908 buffer size 
> or the max network packet size. I thought the SIM908 would handle 
> dividing data into packets as needed. The SIM908 manual mentions the 
> max packet size depends on network status and should be queried by 
> "AT+CIPSEND?". After the overrun net_state_activity() will not 
> recognize "ERROR" to terminate the pending msg, so will run into the 
> timeout and start a network re-init.
>
> My battery status data exceeds 1500 bytes on first run and later on if 
> enough cells need updates. I'll think about how to split up data 
> packets into multiple CIPSENDs. Would be nice if the net functions 
> take care of this transparently.
>
> A secondary issue turned up from the diag log: the SIM908 crashed in 
> the middle of a CIPSEND command while the module continued to run 
> normally. The module still thought it's in NET_STATE_READY, so did not 
> re-initalize the modem. The connection could then be established on 
> the next CIPSTART, but the complete INIT stuff had not been done. So 
> it seems independant SIM908 resets need to be handled as well, and 
> they can occur anytime. I'll see if I can solve that too.
>
> Regards,
> Michael
>
>
> Am 30.12.2012 15:42, schrieb Michael Balzer:
>> I hesitate to merge into the master because I currently have link / 
>> connectivity problems, especially during driving. I introduced a GPS 
>> logging to optimize my antenna positions and managed to get some 
>> really nice tracks three days ago, so I don't think this is related 
>> to my changes... but I'm not 100% sure. I tried different antenna 
>> positions and another GSM network, but the connection keeps dropping 
>> when moving the car, and GPS position updates need minutes. Could be 
>> weather conditions ...or some tricky race condition bug?
>
>
>
>
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-- 
Michael Balzer * Paradestr. 8 * D-42107 Wuppertal
Fon 0202 / 272 2201 * Handy 0176 / 206 989 26

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