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From: <li...@ha...> - 2006-01-20 16:16:51
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Hi, --- Urspr=FCngliche Nachricht --- Datum: 20.01.2006 16:43 Von: Paul Kamphuis <pau...@xs...> > Till, I really like the idea of a $5 DIY USB interface for a HD44780. > What are you planning on using? There's a nice project to do software bit-banging usb with atmel avrs (http://www.obdev.at/products/avrusb/index.html). I flashed the sensor example code onto one of my atmega8 demo boards and it was immediately recognized by my pc. It should be quite simple to add 4 bit lcd interface to this. The firmware doesn't need to know much about the display, since the bwct driver sends the hd44780 commands via usb. I'll only have to do some small tests to e.g. prevent the pc from switching the display into 8bit mode. Other than that i can just forward any command directly to the display. I am planning to allow for two controllers and make contrast and backlighting configurable via usb. Only few parts will be needed besides the avr itself. Even the 40mA for the backlight leds may be driven directly by the avr. The whole device is meant to be open source/open hardware, so you can start heating up the soldering irons ... The whole device will not be 100% usb compliant. The soft-usb implementation does not allow for all the necessary crc checks and the like and the final device will not meet the usb spec regarding power consumption etc. But it should work good enough for most applications. I do understand, that the other usb adaptors are sold with few different display types only. But i'd like to use as much different display as the generic hd44780 driver does. I am still not convinced, that having a seperate usb driver doing much of the same things the generic driver does (e.g. adopting the addressing scheme for 16 col displays) is a clever thing ... Ciao, Till |
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From: <ti...@ha...> - 2006-01-26 09:46:47
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Hi, --- Urspr=FCngliche Nachricht --- Datum: 26.01.2006 09:49 Von: Nico Wallmeier <nic...@po...> An: Till Harbaum <ti...@ha...> Betreff: Re: [Lcd4linux-devel] USB based hd44780 units ... > I've just an other question. Does your layout support a negative > contrast voltage? I've a display which needs a negative contrast voltage... No, it doesn't. I don't have such a display and never had. You'll have to modify the pcb to support this. Ciao, Till |
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From: Michael R. <re...@eu...> - 2006-01-26 10:03:11
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Hi there, >>I've just an other question. Does your layout support a negative >>contrast voltage? I've a display which needs a negative contrast >> voltage... Really? A HD44780 Display with *negative* contrast voltage? Never seen this... anyway, there are very small DC/DC converters which can produce -5V (or even -12V) out of +5V. Look for "RO-0505S", Conrad sells them for about 8=80 bye, Michael --=20 Michael Reinelt <re...@eu...> http://home.pages.at/reinelt GPG-Key 0xDF13BA50 ICQ #288386781 |
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From: Paul K. <pau...@xs...> - 2006-01-20 16:38:41
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Hi Till, I had a very quick look at it. It looks like a very nice and simple solution indeed. I have to look into the BWCT driver, to see what makes it special. But for the I2C interface we created additional support next to the parallel port implementation. My guess would be that for USB something similar would happen. Looking forward to your results, Paul li...@ha... wrote: >Hi, > > --- Ursprüngliche Nachricht --- >Datum: 20.01.2006 16:43 >Von: Paul Kamphuis <pau...@xs...> > > >>Till, I really like the idea of a $5 DIY USB interface for a HD44780. >>What are you planning on using? >> >> >There's a nice project to do software bit-banging usb with atmel avrs >(http://www.obdev.at/products/avrusb/index.html). I flashed the sensor >example code onto one of my atmega8 demo boards and it was immediately >recognized by my pc. It should be quite simple to add 4 bit lcd interface >to this. The firmware doesn't need to know much about the display, since >the bwct driver sends the hd44780 commands via usb. I'll only have to do >some small tests to e.g. prevent the pc from switching the display into >8bit mode. Other than that i can just forward any command directly to the >display. I am planning to allow for two controllers and make contrast and >backlighting configurable via usb. Only few parts will be needed besides >the avr itself. Even the 40mA for the backlight leds may be driven >directly >by the avr. The whole device is meant to be open source/open hardware, so >you can start heating up the soldering irons ... > >The whole device will not be 100% usb compliant. The soft-usb >implementation >does not allow for all the necessary crc checks and the like and the >final >device will not meet the usb spec regarding power consumption etc. But it >should work good enough for most applications. > >I do understand, that the other usb adaptors are sold with few different >display types only. But i'd like to use as much different display as the >generic hd44780 driver does. I am still not convinced, that having a >seperate >usb driver doing much of the same things the generic driver does (e.g. >adopting the addressing scheme for 16 col displays) is a clever thing ... > >Ciao, > Till > > > > > > > > >------------------------------------------------------- >This SF.net email is sponsored by: Splunk Inc. Do you grep through log files >for problems? Stop! Download the new AJAX search engine that makes >searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! >http://sel.as-us.falkag.net/sel?cmd_______________________________________________ >Lcd4linux-devel mailing list >Lcd...@li... >https://lists.sourceforge.net/lists/listinfo/lcd4linux-devel > > > > > |
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From: Michael R. <re...@eu...> - 2006-01-21 10:38:08
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Hi there, > I have to look into the BWCT driver, to see what makes > it special. But for the I2C interface we created additional support next > to the parallel port implementation. My guess would be that for USB > something similar would happen. Okay, guys, consider me being convinced :-) I agree there should be a 'drv_generic_usb' backend, which can be used in the HD44780 driver, too. But there will be some issues with the autoconf stuff again... (did I mention that I *love* autoconf?) Another possibility would be to create a generic HD44780 backend, which could be used by different drivers.... so there would be two (or three) HD44780 drivers: one for parport, one for i2c, and some for USB. What I really dislike is the complexity of the drv_HD44780.c file. And I suppose complexity will increase again if we add another bus type... One of the 'special' things with the BWCT driver is the strange display detection. The reason is that there are different BWCT interfaces, sometimes there's a different interface class or something.... I remember a discussion with Bernd from BWCT about this... bye, Michael -- Michael Reinelt <re...@eu...> http://home.pages.at/reinelt GPG-Key 0xDF13BA50 ICQ #288386781 |
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From: Till H. <ti...@ha...> - 2006-01-21 10:38:48
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Hi, the first prototype is working now: http://www.harbaum.org/till/prototyp.jpg It can be used with the current bwct driver from lcd4linux. As you can see, i am using it with a 4*20 lcd. Software contrast works as well. I still have to add support for the backlight and a second controller, but despite that, the concept is working. I wonder if i'd produce a small set of industry quality pcbs. They should be about $5 each. Is anyone interested? Regards, Till -- Dr.Ing. Till Harbaum, ti...@ha... |
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From: Michael R. <re...@eu...> - 2006-01-21 10:56:13
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Hi Till, > the first prototype is working now: > > http://www.harbaum.org/till/prototyp.jpg Hey, great! > I wonder if i'd produce a small set of industry quality pcbs. They > should be about $5 each. Is anyone interested? I AM, I AM, I AM!! And I need a schematics, and, most important, a part list. I'm afraid I have to visit Conrad today :-( (I hope my girlfriend doesn't notice) bye, Michael -- Michael Reinelt <re...@eu...> http://home.pages.at/reinelt GPG-Key 0xDF13BA50 ICQ #288386781 |
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From: Michael R. <re...@eu...> - 2006-01-21 10:47:04
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Hi, > There's a nice project to do software bit-banging usb with atmel avrs > (http://www.obdev.at/products/avrusb/index.html). I had a look at this stuff, sonds very interesting! I don't know much about USB and/or AVR, but I read that things are very timing-critical. Looks like the 12MHz of the AVR are very tight, one has to use every single available cycle just to read the bits from USB. I wonder how the AVR shoud handle the display, too? > I do understand, that the other usb adaptors are sold with few different > display types only. But i'd like to use as much different display as the > generic hd44780 driver does. I am still not convinced, that having a > seperate > usb driver doing much of the same things the generic driver does (e.g. > adopting the addressing scheme for 16 col displays) is a clever thing ... See my other mail. I agree with you. But I'm still unhappy with the complexity of drv_HD44780.c There are so many things which are used with the parport only (4/8 bit mode, busy-flag checking, all the timing stuff, ....) For the development of the hardware, I suggest using a seperate driver like the BWCT. If we know that the hardware and the driver work, we can integrate it into the HD44780 driver. bye, Michael -- Michael Reinelt <re...@eu...> http://home.pages.at/reinelt GPG-Key 0xDF13BA50 ICQ #288386781 |
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From: Nico W. <nic...@po...> - 2006-01-21 11:15:06
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Hi Till, >> I wonder if i'd produce a small set of industry quality pcbs. They >> should be about $5 each. Is anyone interested? > I AM, I AM, I AM!! I am interested too ;-) Bye, Nico |
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