**** BEGIN LOGGING AT Sat Jul 16 23:59:56 2005
Jul 17 18:36:42 <VoodooZ> [g2], ping
Jul 17 19:02:05 <[g2]> VoodooZ, pong
Jul 17 19:04:40 <VoodooZ> Hey, 
Jul 17 19:04:52 <VoodooZ> Are you guys using USB on your JTAG project?
Jul 17 19:05:33 <[g2]> ep1220 is
Jul 17 19:06:07 <VoodooZ> I"m asking because I apparently managed to burn my I2C bus AGAIN! I have no clue what happened but the RTC is not responding anymore.
Jul 17 19:06:48 <VoodooZ> So I'm considering building a USB hub using an AVR that will extend I/O out and read other sensors so my slug can read it all in one big chunk via USB.
Jul 17 19:07:42 <Tiersten> Have you reset the RTC?
Jul 17 19:08:19 <VoodooZ> Irregardless. I rebooted and all and it still doesn't work with no other i2c devices on the bus.
Jul 17 19:08:40 <[g2]> bummer :(
Jul 17 19:08:42 <VoodooZ> I was just curious to know how hard it would be to code for USB data xfer
Jul 17 19:09:02 <VoodooZ> I don't feel like buying another one when this one still works fine.
Jul 17 19:09:19 <VoodooZ> I don't care much about time. I'm just afraid linux might not like it though. ???
Jul 17 19:09:24 <Tiersten> It doesn't respond at all?
Jul 17 19:10:06 <VoodooZ> nope.
Jul 17 19:10:44 <VoodooZ> but that's ok as I always wanted to learn to program USB.
Jul 17 19:11:10 <VoodooZ> I noticed quite a big frame rate drop when using the software I2C anyways so...
Jul 17 19:11:56 <Tiersten> Linux will be fine with the lack of RTC
Jul 17 19:12:04 <Tiersten> It will just start over at a fixed time each time you reboot
Jul 17 19:12:11 <VoodooZ> good. 
Jul 17 19:12:41 <VoodooZ> I just hope it won't keep trying to access it until it times out as the bootup times is already long enough like that. :)
Jul 17 19:13:07 <Tiersten> Remove the RTC driver if you want to stop that
Jul 17 19:13:18 <VoodooZ> ok.
Jul 17 19:13:37 <Tiersten> It will time out but it'll be faster just without it
Jul 17 19:13:43 <VoodooZ> Should I have my robot code make USB calls or have the kernel do it. is this what libusb does? userspace?
Jul 17 19:14:11 <Tiersten> Yeah.  libusb is a userspace library to talk to USB devices
Jul 17 19:14:28 <Tiersten> Is it actually 100% working now?  I thought it was good enough for scanning now but there were still some underlying flaws?
Jul 17 19:14:40 <VoodooZ> I heard bad things about it.
Jul 17 19:15:14 <VoodooZ> so I guess I'd be better off writing an actual kernel driver module for my USB device and have my robot code mmap it right?
Jul 17 19:15:22 <Tiersten> You can do what puppy does and directly access usbfs
Jul 17 19:15:23 <dyoung> look at puppy.
Jul 17 19:15:24 <Tiersten> That should work
Jul 17 19:15:27 <dyoung> echo
Jul 17 19:15:29 <dyoung> :-)
Jul 17 19:15:31 <Tiersten> :)
Jul 17 19:15:44 <Tiersten> mmap it?
Jul 17 19:15:44 <VoodooZ> really? much simpler probably too right?
Jul 17 19:15:47 <Tiersten> ew
Jul 17 19:16:14 <VoodooZ> I'll be mostly requesting a block of data every iterations of the sensor loop and then writing the motor commands out
Jul 17 19:16:18 <Tiersten> It's not as simple as just using libusb but it's easier than writing a whole driver
Jul 17 19:16:31 <VoodooZ> ok.
Jul 17 19:16:48 <VoodooZ> I'm starting to read about USB and how the protocol is handled. 
Jul 17 19:17:05 <Tiersten> AVRs have built in USB?
Jul 17 19:17:05 <VoodooZ> command packets vs the others and all...
Jul 17 19:17:11 <Tiersten> (Not looked at them recently)
Jul 17 19:17:19 <VoodooZ> the newer ones apparently do
Jul 17 19:17:28 <Tiersten> You basically have multiple channels called endpoints (don't ask.  it's a stupid name yes)
Jul 17 19:17:35 <Tiersten> Each one is only one direction
Jul 17 19:17:43 <VoodooZ> but I might actually try that software based USB stack for the AVRs first.
Jul 17 19:17:45 <Tiersten> You can have 16 both ways.  0 is always the control channel
Jul 17 19:17:48 <VoodooZ> i see.
Jul 17 19:18:05 <Tiersten> The AVRs have the required hardware though yes?
Jul 17 19:18:11 <VoodooZ> So I would request one for reading and one for sending my motor commands.
Jul 17 19:18:21 <Tiersten> I wouldn't try interfacing one that doesn't have the USB hardware
Jul 17 19:18:35 <VoodooZ> really?
Jul 17 19:18:53 <Tiersten> Yes.  There are strict timing requirements
Jul 17 19:19:05 <VoodooZ> I don't want to have one of those FTDI USB 2 serial chip thingy as they limit me.
Jul 17 19:19:07 <Tiersten> You can't just bitbang it out like serial
Jul 17 19:19:36 <VoodooZ> yeah, but it works. It's limited to 1.5mbit but that's enough. It's still plenty fast comapred to 100Khz I2C.
Jul 17 19:19:48 <Tiersten> what works?
Jul 17 19:20:06 <VoodooZ> the AVRUSB thing. check it out:http://www.obdev.at/products/avrusb/
Jul 17 19:20:30 <VoodooZ> There is another opensource one around too.
Jul 17 19:20:43 <VoodooZ> and it even uses my favorite AVR! mega8.
Jul 17 19:20:53 <Tiersten> ew.  bitbanged USB
Jul 17 19:21:00 <Tiersten> it is the slow one however
Jul 17 19:21:08 <Tiersten> Only mice and keyboards really use that speed
Jul 17 19:21:11 <VoodooZ> slow what? USB mode?
Jul 17 19:21:14 <Tiersten> Yes
Jul 17 19:21:28 <VoodooZ> Wouldn't that be plenty for motor commands at 20Hz?
Jul 17 19:21:42 <Tiersten> How tight are you timing requirements?
Jul 17 19:21:45 <Tiersten> are your
Jul 17 19:21:57 <VoodooZ> I read sensors and write resulting motor commands every 40-60ms.
Jul 17 19:22:03 <VoodooZ> Not that tight.
Jul 17 19:22:07 <Tiersten> It's okay if you miss it by a few ms however?
Jul 17 19:22:14 <VoodooZ> I guess.
Jul 17 19:22:29 <VoodooZ> Until I realise otherwise :)
Jul 17 19:22:32 <Tiersten> Should be okay then...
Jul 17 19:23:03 <Tiersten> It's not isosynchronous so you're not gauranteed when it will complete
Jul 17 19:23:18 <VoodooZ> well, I'll give it a quite try anyways. cheaper and faster that buying a new AVR.
Jul 17 19:23:23 <Tiersten> Yeah
Jul 17 19:23:24 <VoodooZ> that's fine.
Jul 17 19:23:29 <VoodooZ> for now at least.
Jul 17 19:23:52 <VoodooZ> so I'll check that puppy package then.
Jul 17 19:24:00 <Tiersten> Yup
Jul 17 19:24:14 <Tiersten> Your AVR run at 12MHz?
Jul 17 19:24:19 <VoodooZ> and then If I feel more advanturous I'll write my own driver.
Jul 17 19:24:23 <VoodooZ> 16Mhz
Jul 17 19:24:32 <VoodooZ> which is overkill in most cases.
Jul 17 19:24:37 <Tiersten> You'll have to change it for 12MHz
Jul 17 19:25:04 <Tiersten> Timing again
Jul 17 19:25:05 <VoodooZ> yeah, but just the master one which will talk to the slug and fetch updates from all the sensors.
Jul 17 19:25:41 <VoodooZ> I might have it read the sensors via I2C so it will essentially become a USB-to-I2C hub.
Jul 17 19:25:47 <Tiersten> Depending on how tight the timing requirements of the code are, you might need to dedicate a single AVR to do the USB and another one to do everything else.  Not hard though and still cheap
Jul 17 19:25:56 <Tiersten> Depends on how much stuff you're actually doing
Jul 17 19:26:10 <VoodooZ> yep. exactly what I wanted to do.
Jul 17 19:26:16 <VoodooZ> not that much. 
Jul 17 19:26:27 <Tiersten> What on earth are you doing to the I2C bus anyway??
Jul 17 19:26:36 <VoodooZ> I already have mega8's co-processors for most of my sensors
Jul 17 19:26:45 <VoodooZ> and one on the motor controller.
Jul 17 19:27:05 <VoodooZ> I have no clue yet. I must have zapped it with 5V by accident. 
Jul 17 19:27:14 <VoodooZ> It was too slow anyways.
Jul 17 19:27:16 <VoodooZ> :)
Jul 17 19:27:19 <Tiersten> that's what you did the first time around though!
Jul 17 19:27:29 <Tiersten> you like wearing wool jumpers? :)
Jul 17 19:27:33 <VoodooZ> yeah I know :(
Jul 17 19:27:58 <VoodooZ> I noticed quite a performance dropped in my vision code when actually enabling the I2C read.
Jul 17 19:28:20 <VoodooZ> so that will help motivate me to move to USB.
Jul 17 19:28:27 <VoodooZ> which I was too lazy to do in the first place. 
Jul 17 19:28:38 <VoodooZ> Plus It's good experience.
Jul 17 19:28:57 <Tiersten> yeah
Jul 17 19:29:26 <Tiersten> you using a USB camera?
Jul 17 19:29:37 <VoodooZ> yep
Jul 17 19:29:41 <VoodooZ> usb 2.0!
Jul 17 19:30:04 <VoodooZ> there was no driver so I had to hack the experimental one from a guy I found online.
Jul 17 19:30:23 <VoodooZ> so I have good example code if I ever move to a kernel module.
Jul 17 19:30:30 <VoodooZ> (for my I/O module)
Jul 17 19:30:57 <Tiersten> Use a FPGA ;)
Jul 17 19:31:26 <VoodooZ> heheheh
Jul 17 19:31:43 <VoodooZ> I know! that's another thing I want to try eventually. but It's overkill for now/
Jul 17 19:33:03 <VoodooZ> I just tried the RTC again (running on AC instead of battery this time) and it still fails so...
Jul 17 19:33:14 <[g2]> Tiersten, hey FPGA boy... when are you gonna sends some VHDL/Verilog our way ?
Jul 17 19:33:17 <[g2]> :)
Jul 17 19:33:25 <VoodooZ> I guess the RTC module is just another module built internally right?
Jul 17 19:33:30 <VoodooZ> hehe
Jul 17 19:34:22 * Tiersten starts to whistle nonchalantly
Jul 17 19:34:31 <Tiersten> You'll have to talk to ka6sox when he gets back :)
Jul 17 19:42:03 <VoodooZ> Tiersten, here's the original AVRUSB: http://www.cesko.host.sk/
Jul 17 19:43:35 <Tiersten> Thanks
Jul 17 20:26:39 <VoodooZ> night
**** ENDING LOGGING AT Sun Jul 17 23:59:57 2005