I have a patch in my AVR32 linux serial driver I really ought to
I do need outgoing CTS control, though I would assume it should work
character by character. I found that you can talk to GSM modems without
it, but it falls over at awkward moments.
My experience with incoming comms is that the best strategy is to assign
an oodle of RAM to the buffer - of course the definition of that can be a
bit woolly :-)
The RTS/CTS stuff on the AP7000 CPU is pretty special overall, I love
that it even includes a mode to interface to an RS485 driver!
But thanks for the heads-up.
> *From:* "martinwguy" <[hidden email]>
> *To:* <[hidden email]>
> *Date:* Thu, 27 Sep 2012 19:39:32 +0200
> On 27 September 2012 19:31, martinwguy <[hidden email]> wrote:
> >> So no screen.... certainly one model with no Ethernet.
> >> Couple of UARTS
> >> Ethernet would be good to run Modbus TCPIP if it is simple
> Sorry, forgot to comment on this:
> The AVR32UC3A0 chip has two UARTS, both available on Mizar's bus
> headers, but hardware flow control does not work in eLua with this
> chip. I got as far as figuring out what was needed but not as far as
> implementing it.
> The issue is
> https://code.google.com/p/mizar32/issues/detail?id=29 -
> in summary, HW flow control only works automatically when you use
> to drive the UART. Without DMA, if you enable HW flow control, the
> device will respect CTS before sending data, but code is needed to
> wiggle RTS up and down manually to stop the other end from flooding
> If you need RTSCTS hardware flow control, that suggests using a
> different SoC.
> I've seen most RTS/CTS issues over the years.
> I have a patch in my AVR32 linux serial driver I really ought to
> I do need outgoing CTS control, though I would assume it should work
> character by character. I found that you can talk to GSM modems without
> it, but it falls over at awkward moments.
> My experience with incoming comms is that the best strategy is to assign
> an oodle of RAM to the buffer - of course the definition of that can be a
> bit woolly :-)
...which is what I did to alleviate it...
> The RTS/CTS stuff on the AP7000 CPU is pretty special overall, I love
> that it even includes a mode to interface to an RS485 driver!
The AVR32UC3A0 series has 485 mode only in UART1, not UART0. We only
discovered this after manufacturing 500 serial port add-on boards for
the Mizar32 with also an RS485 connector, amplifier and mode switch
placed on UART0 :-(
Fortunately for us, eLua doesn't have RS485 support yet so we are
hoping nobody will try to use the RS485 mode on UART0 until we fix
Worse, the RTS and CTS pins are swapped on the connector because our
guy trusted the AVR32 EVK1100 devboard schematics over his own
judgment, and they are totally unusable on that board as they are
swapped twice there, so go in the wrong side of the amplifiers on
their way to the connector. Fortunately he only swapped the pins on
the connector thinking that AVR couldn't have got it wrong, but failed
to copy the other error so the signals would work at an electrical
level if eLua had support for them,