[iyonix-support] Re: Iyonix driving K8055 board via USB - very slow?
- From: "Neil F" <faz@xxxxxxxxxxxxx>
- To: <iyonix-support@xxxxxxxxxxxxx>
- Date: Thu, 6 Aug 2009 11:20:31 +0100
-----Original Message-----
From: iyonix-support-bounce@xxxxxxxxxxxxx
[mailto:iyonix-support-bounce@xxxxxxxxxxxxx] On Behalf Of dave higton
Sent: 03 August 09 11:16
To: iyonix-support@xxxxxxxxxxxxx
Subject: [iyonix-support] Re: Iyonix driving K8055 board via USB -
very slow?
There is no 10 ms limit inherent in USB in general.
The K8055 board uses a particularly lame 8-bit CPU - a PIC - so I
think you'll find that's the limit to what you want to do.
I've programmed an STR711 to do two embedded jobs. It's a far more
powerful CPU (an ARM that will run at up to around 32 MHz), and
Olimex do very low cost header boards and development boards. If
you use a more powerful CPU, and one that you can programme yourself,
you can implement a higher level protocol, which would require less
transactions from the host. You can get an excellent tool set free
from IAR, though you will at some stage need a J-Link JTAG programmer,
so an IAR development kit would be good value for money. I would
commend that approach, or a similar one, to you.
Dave
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Thanks Dave. And thanks for writing the original USB prog BTW, been
very handy.
It seems there is a 10ms max cycle time for 'slow-speed' USB 1.1
devices, which I'm sure this card is (see Thomas' post), so that might
account for the 10ms cycle I'm finding when I try to speed things up.
Then again, as you say, this is an inherently slow card - it's quoted
as having a 20ms minimum response time per command. That's presumably
because it has to cycle round logging or setting all the individual
analogue and digital in/outs once for each command sent.
Thanks for help - at least I know I haven't got a faulty card.
-Neil.
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