On Feb 16, 12:39=A0pm, John Devereux <j...@devereux.me.uk> wrote:
> Tim Wescott <t...@seemywebsite.com> writes:
> > On Wed, 15 Feb 2012 22:18:01 -0600, Les Cargill wrote:
>
> >> Tim Wescott wrote:
> >>> I came across this schematic (well, my son dragged it into my
> >>> attention):
> >>>http://www.otd.kr/data/file/
> > pj_LIMKB/1964092542_24157b90_Aikon28LIMKB29-
> >>> SMD_Schematic.PNG
>
> >>> This is for a universal keyboard controller. =A0The thing that is rea=
lly
> >>> catching my eye, though, is that the thing appears to be set up to bi=
t-
> >>> bang the USB.
>
> >>> Has anyone ever heard of doing this? =A0Tried it? =A0Succeeded? =A0US=
B slow
> >>> is 1.5MHz, so there's a remote possibility that one might possibly ha=
ve
> >>> enough time to do something if the processor isn't doing much else (t=
he
> >>> processor in the above schematic is clocking at 12MHz), but I'm prett=
y
> >>> astonished that they're even managing that.
>
> >> That's from PD0(RXD) and PD2(INT0)? Are those configured then as just
> >> PIO (emphasis O)?
>
> >> Pretty crazy, but keyboard events are relatively infrequent - hundreds
> >> per second at most.
>
> > I have absolutely no clue how it's configured -- the source code isn't
> > available. =A0I'm still trying to get past bit-banged USB.
>
> Not done it myself, but I know that there has been code around for ages
> for Atmel. Low speed USB is relatively.... low speed, and AIUI USB was
> designed to be relatively simple on the device side.
>
>I have absolutely no clue how it's configured -- the source code isn't
>available. I'm still trying to get past bit-banged USB.
In addition to OBdev's VUSB, there's an open-source project called
USBtiny --- very similar to VUSB: runs on AVRs, bit-bangs low-speed USB.
http://dicks.home.xs4all.nl/avr/usbtiny/
"The software is written for an AVR clocked at 12 MHz. At this
frequency, each bit on the USB bus takes 8 clock cycles, and with a lot
of trickery, it is possible to decode and encode the USB waveforms by
software. The USB driver needs approximately 1250 to 1350 bytes of flash
space"[....]
Reply by lang...@fonz.dk●February 17, 20122012-02-17
On 16 Feb., 04:34, Tim Wescott <t...@seemywebsite.please> wrote:
> I came across this schematic (well, my son dragged it into my attention):=
> SMD_Schematic.PNG
>
> This is for a universal keyboard controller. =A0The thing that is really
> catching my eye, though, is that the thing appears to be set up to bit-
> bang the USB.
>
> Has anyone ever heard of doing this? =A0Tried it? =A0Succeeded? =A0USB sl=
ow is
> 1.5MHz, so there's a remote possibility that one might possibly have
> enough time to do something if the processor isn't doing much else (the
> processor in the above schematic is clocking at 12MHz), but I'm pretty
> astonished that they're even managing that.
>
> --
> Tim Wescott
> Control system and signal processing consultingwww.wescottdesign.com
there has been slow speed bit banged usb for a long time, think this
is one
of the more "famous" ones:
http://www.obdev.at/products/vusb/index.html
it is for AVR and I think it runs at most frequencies from 8MHz up,
-Lasse
Reply by Ivan Shmakov●February 17, 20122012-02-17
>>>>> Tim Wescott <tim@seemywebsite.please> writes:
> I came across this schematic (well, my son dragged it into my
> attention):
> http://www.otd.kr/data/file/pj_LIMKB/1964092542_24157b90_Aikon28LIMKB29-
> SMD_Schematic.PNG
> This is for a universal keyboard controller. The thing that is
> really catching my eye, though, is that the thing appears to be set
> up to bit- bang the USB.
I'm somewhat surprised by the fact that V-USB [1] wasn't
explicitly mentioned in this thread.
[1] http://obdev.at/products/vusb/
> Has anyone ever heard of doing this? Tried it? Succeeded?
Once, I've built a simplistic USB device based on ATmega8 (or a
similar MCU) and V-USB, which was talking USB-MIDI to the host.
As V-USB had no USB-MIDI-specific parts back then (and I wonder
if they have it nowadays) I had to check the "reference", for
which I've used the source code of the Linux kernel.
> USB slow is 1.5MHz, so there's a remote possibility that one might
> possibly have enough time to do something if the processor isn't
> doing much else (the processor in the above schematic is clocking at
> 12MHz), but I'm pretty astonished that they're even managing that.
--
FSF associate member #7257
Reply by Tilmann Reh●February 17, 20122012-02-17
Tim Wescott schrieb:
> I came across this schematic (well, my son dragged it into my attention):
> http://www.otd.kr/data/file/pj_LIMKB/1964092542_24157b90_Aikon28LIMKB29-
> SMD_Schematic.PNG
>
> This is for a universal keyboard controller. The thing that is really
> catching my eye, though, is that the thing appears to be set up to bit-
> bang the USB.
>
> Has anyone ever heard of doing this? Tried it? Succeeded? USB slow is
> 1.5MHz, so there's a remote possibility that one might possibly have
> enough time to do something if the processor isn't doing much else (the
> processor in the above schematic is clocking at 12MHz), but I'm pretty
> astonished that they're even managing that.
On Thu, 16 Feb 2012 12:43:45 +0000, Simon Clubley wrote:
> On 2012-02-15, Tim Wescott <tim@seemywebsite.com> wrote:
>> On Wed, 15 Feb 2012 22:18:01 -0600, Les Cargill wrote:
>>> That's from PD0(RXD) and PD2(INT0)? Are those configured then as just
>>> PIO (emphasis O)?
>>>
>>> Pretty crazy, but keyboard events are relatively infrequent - hundreds
>>> per second at most.
>>
>> I have absolutely no clue how it's configured -- the source code isn't
>> available. I'm still trying to get past bit-banged USB.
>>
>>
> :-)
>
> Well you never know what crazy stuff you can justify when you have the
> freedom to play with this stuff on your own time (and are funding it out
> of your own pocket) instead of having to charge per hour of your time.
> :-)
>
> Never underestimate the ingenuity of a hobbyist looking to save a few
> pounds/dollars by building their own device instead of using a
> preassembled widget.
>
> The cost versus time tradeoffs for someone like myself are completely
> different from those experienced by a embedded person like yourself who
> is doing this for a living.
>
> BTW, I'm amused that you are astonished by this and it did make me
> wonder what other things people building things out of their own pocket
> can justify which would astonish a person doing this for a living. :-)
It'd make sense in a system that ships in high volume, too -- if
production is going to be 100/year and you save a penny on the BOM, then
every year you've made a buck. If production is 10000 a month and you
save a penny on the BOM, then every year you've made $1200 -- so the
amount of engineering time you should spend to save that penny varies
depending on who you're working for, and what they're doing.
--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?
Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com
Reply by Tim Wescott●February 16, 20122012-02-16
On Thu, 16 Feb 2012 12:42:38 -0600, Les Cargill wrote:
> Tim Wescott wrote:
>> On Wed, 15 Feb 2012 22:18:01 -0600, Les Cargill wrote:
>>
>>> Tim Wescott wrote:
>>>> I came across this schematic (well, my son dragged it into my
>>>> attention):
>>>> http://www.otd.kr/data/file/
>> pj_LIMKB/1964092542_24157b90_Aikon28LIMKB29-
>>>> SMD_Schematic.PNG
>>>>
>>>> This is for a universal keyboard controller. The thing that is
>>>> really catching my eye, though, is that the thing appears to be set
>>>> up to bit- bang the USB.
>>>>
>>>> Has anyone ever heard of doing this? Tried it? Succeeded? USB slow
>>>> is 1.5MHz, so there's a remote possibility that one might possibly
>>>> have enough time to do something if the processor isn't doing much
>>>> else (the processor in the above schematic is clocking at 12MHz), but
>>>> I'm pretty astonished that they're even managing that.
>>>>
>>>>
>>>>
>>> That's from PD0(RXD) and PD2(INT0)? Are those configured then as just
>>> PIO (emphasis O)?
>>>
>>> Pretty crazy, but keyboard events are relatively infrequent - hundreds
>>> per second at most.
>>
>> I have absolutely no clue how it's configured -- the source code isn't
>> available. I'm still trying to get past bit-banged USB.
>>
>>
>
> I seem to be beyond surprise any more. What's the jitter spec for USB,
> anyway?
I don't know. I've pulled out my USB book and I'm reading it.
--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?
Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com
Reply by Les Cargill●February 16, 20122012-02-16
Tim Wescott wrote:
> On Wed, 15 Feb 2012 22:18:01 -0600, Les Cargill wrote:
>
>> Tim Wescott wrote:
>>> I came across this schematic (well, my son dragged it into my
>>> attention):
>>> http://www.otd.kr/data/file/
> pj_LIMKB/1964092542_24157b90_Aikon28LIMKB29-
>>> SMD_Schematic.PNG
>>>
>>> This is for a universal keyboard controller. The thing that is really
>>> catching my eye, though, is that the thing appears to be set up to bit-
>>> bang the USB.
>>>
>>> Has anyone ever heard of doing this? Tried it? Succeeded? USB slow
>>> is 1.5MHz, so there's a remote possibility that one might possibly have
>>> enough time to do something if the processor isn't doing much else (the
>>> processor in the above schematic is clocking at 12MHz), but I'm pretty
>>> astonished that they're even managing that.
>>>
>>>
>>
>> That's from PD0(RXD) and PD2(INT0)? Are those configured then as just
>> PIO (emphasis O)?
>>
>> Pretty crazy, but keyboard events are relatively infrequent - hundreds
>> per second at most.
>
> I have absolutely no clue how it's configured -- the source code isn't
> available. I'm still trying to get past bit-banged USB.
>
Also, wasn't one of the old-school UARTs (the 8530/82530 ) just ...
like... a Z80 with special firmware & some peripherals? They'd do T1
rate, if not more... I only used 'em for mid-speed Iloop and RS232/422
before the 68360 & descendents came along...
I know the 16550 predecessors were not.
--
Les Cargill
Reply by Les Cargill●February 16, 20122012-02-16
Tim Wescott wrote:
> On Wed, 15 Feb 2012 22:18:01 -0600, Les Cargill wrote:
>
>> Tim Wescott wrote:
>>> I came across this schematic (well, my son dragged it into my
>>> attention):
>>> http://www.otd.kr/data/file/
> pj_LIMKB/1964092542_24157b90_Aikon28LIMKB29-
>>> SMD_Schematic.PNG
>>>
>>> This is for a universal keyboard controller. The thing that is really
>>> catching my eye, though, is that the thing appears to be set up to bit-
>>> bang the USB.
>>>
>>> Has anyone ever heard of doing this? Tried it? Succeeded? USB slow
>>> is 1.5MHz, so there's a remote possibility that one might possibly have
>>> enough time to do something if the processor isn't doing much else (the
>>> processor in the above schematic is clocking at 12MHz), but I'm pretty
>>> astonished that they're even managing that.
>>>
>>>
>>
>> That's from PD0(RXD) and PD2(INT0)? Are those configured then as just
>> PIO (emphasis O)?
>>
>> Pretty crazy, but keyboard events are relatively infrequent - hundreds
>> per second at most.
>
> I have absolutely no clue how it's configured -- the source code isn't
> available. I'm still trying to get past bit-banged USB.
>
I seem to be beyond surprise any more. What's the
jitter spec for USB, anyway?
--
Les Cargill
Reply by ●February 16, 20122012-02-16
Tim Wescott <tim@seemywebsite.please> wrote:
> Has anyone ever heard of doing this? Tried it? Succeeded?