The protocol limits the write size to 256 and read size to 255. The hardware buffers are 256 for writing (4 byte overhead for each transaction) and 128 for reading (1 byte overhead for each transaction). I don't see a reason why 78 would be a cutoff point. What do you mean by "get a timeout"? Do you have a logic analyzer by any chance, to figure out what's happening on the wire?
On Tue, Dec 16, 2014 at 1:36 PM, Mark Melvin <[email protected]> wrote: > > Hi Guys, > > I've been experimenting with I2C, and found that if I try to send the TWI > master anything more than about 78 bytes of data, it doesn't work. I'll > either get a timeout, or the IOIO will forcibly disconnect. Lowering my > maximum transaction size to <=78 seems to make it behave reliably. > > Is there some internal buffer that is overflowing here? I can't find > anything obvious in the code. I see there are RX and TX buffers in the PIC > code, but they are 128 and 256 bytes, bigger than the limitation I am > seeing. And I would think this would be invisible to the user anyway, so > perhaps there is something at the protocol level in Java? > > Thanks, > Mark. > > -- > You received this message because you are subscribed to the Google Groups > "ioio-users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/ioio-users. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "ioio-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/ioio-users. For more options, visit https://groups.google.com/d/optout.
