Re: [fpc-pascal] How to use UART of ARM platforms (e.g. Raspberry Pi ) through free Pascal?
On 07/04/2013 09:09 AM, Paul Breneman wrote: On 07/04/2013 05:08 AM, Dennis Poon wrote: thanks. I am not using the fpc email as it seems off topic. May I know the exact brand and model number of the adapter you used? I have an ATEN usb-to-serial cable (UC-232A) but I am not sure how to connect its serial pins to rs-485 's DIFFERENTIAL LINES and how to set that adapter into half-duplex translation mode. Dennis My favorite is the USB-RS485-WE-1800-BT made by FTDI. It is sold by many companies: http://www.ftdichip.com/Products/Cables/USBRS485.htm It supports 24000 baud which many other adapters don't. I've only used it under Windows but as it is made by FTDI I would think using it under Linux should be no problem. www.CtrlTerm.com has Synapse and SynaSer code that should work on the RPi (for serial and TCP/IP communication) as I did test that recently. Please let me know if you have any problems and I will do further testing on my RPi. Here is my favorite USB to RS-232 serial adapter (4 port, sold at Amazon, has FTDI chipset): http://www.gearmo.com/shop/gm-ftdi4x/ This worked on my RPi. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] How to use UART of ARM platforms (e.g. Raspberry Pi ) through free Pascal?
On 07/03/2013 06:36 PM, Dennis Poon wrote: Can you give me some pointer on directly using UART? I need to implement half-duplex using UART for rs-485 protocol. In a Linux system, accessing the hardware by user code is strictly discouraged, at least whenever interrupts are involved (as with UARTs). A decent system should provide rs-485 support in the TTY driver, when the hardware allows for such. If your system does not do so, you should find or do a device driver yourself. In fact what do you mean by rs-485 protocol ? With RS-485 hardware you can - and supposedly need to - do half-duplex with output enable, if your hardware provides this. The hardware might or might not provide automatic output enable (if not, you need to set and reset RTS in software). The hardware might or might not provide echo cancellation (if not the software needs to actively ignore anything that the hardware echoes back when sending it). If your hardware provides both auto output enable and echo cancellation, your software can happily ignore the rs-485 protocol. Usually both can be done in userland software even with standard TTY drivers that (usually do) setting and resetting support RTS, or (better) by dedicated support in the device driver. -Michael ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] How to use UART of ARM platforms (e.g. Raspberry Pi ) through free Pascal?
On 2013-07-03 16:44, Dennis Poon wrote:
Michael,
I used the synapser.pas unit but the compiler choked at line 232 at the
identifier 'B50', 'B576000' not found.
Any idea ?
I believe you have an outdated version on Synapse then... Here is my
version of the code snippet you posted - and it compiles fine under
Windows, Linux and FreeBSD. I must confess, I had to make a minor tweak
to my synapser.pas unit for FPC 2.6.2 under FreeBSD to compile that unit
- but that change was in a different place in the synapser.pas unit you
mentioned.
-
const
{$IFDEF UNIX}
{$IFDEF BSD}
MaxRates = 18; //MAC
{$ELSE}
MaxRates = 30; //UNIX
{$ENDIF}
{$ELSE}
MaxRates = 19; //WIN
{$ENDIF}
Rates: array[0..MaxRates, 0..1] of cardinal =
(
(0, B0),
(50, B50),
(75, B75),
(110, B110),
(134, B134),
(150, B150),
(200, B200),
(300, B300),
(600, B600),
(1200, B1200),
(1800, B1800),
(2400, B2400),
(4800, B4800),
(9600, B9600),
(19200, B19200),
(38400, B38400),
(57600, B57600),
(115200, B115200),
(230400, B230400)
{$IFNDEF BSD}
,(460800, B460800)
{$IFDEF UNIX}
,(50, B50),
(576000, B576000),
(921600, B921600),
(100, B100),
(1152000, B1152000),
(150, B150),
(200, B200),
(250, B250),
(300, B300),
(350, B350),
(400, B400)
{$ENDIF}
{$ENDIF}
);
{$ENDIF}
{$IFDEF BSD}
const // From fcntl.h
O_SYNC = $0080; { synchronous writes }
{$ENDIF}
-
Regards,
- Graeme -
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Re: [fpc-pascal] How to use UART of ARM platforms (e.g. Raspberry Pi ) through free Pascal?
Michael Schnell wrote: On 07/03/2013 06:36 PM, Dennis Poon wrote: Can you give me some pointer on directly using UART? I need to implement half-duplex using UART for rs-485 protocol. In a Linux system, accessing the hardware by user code is strictly discouraged, at least whenever interrupts are involved (as with UARTs). A decent system should provide rs-485 support in the TTY driver, when the hardware allows for such. If your system does not do so, you should find or do a device driver yourself. In fact what do you mean by rs-485 protocol ? With RS-485 hardware you can - and supposedly need to - do half-duplex with output enable, if your hardware provides this. After days of google search, I am afraid the bcm2835, the Soc of Raspberry Pi (the hardware I have to use) does not provide this hardware support :-( It states that it does not even support interrupt. Polling is the only way for events :-( The hardware might or might not provide automatic output enable (if not, you need to set and reset RTS in software). The hardware might or might not provide echo cancellation (if not the software needs to actively ignore anything that the hardware echoes back when sending it). If your hardware provides both auto output enable and echo cancellation, your software can happily ignore the rs-485 protocol. Usually both can be done in userland software even with standard TTY drivers that (usually do) setting and resetting support RTS, or (better) by dedicated support in the device driver. I have no experience in the above tasks you mentioned :-( It's going to take many days of trial and error. ha.. Thanks for your advice. Dennis ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] How to use UART of ARM platforms (e.g. Raspberry Pi ) through free Pascal?
On 07/04/2013 11:16 AM, Dennis Poon wrote: am afraid the bcm2835, the Soc of Raspberry Pi (the hardware I have to use) does not provide this hardware support :-( It states that it does not even support interrupt. Polling is the only way for events :-( As already discussed here the RPI is strictly meant for educational use and not very suitable for embedded designs (that I think is the only kind of projects that use field-bus specifications such as RS-485). So I recommend using a different board. -Michael ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] How to use UART of ARM platforms (e.g. Raspberry Pi ) through free Pascal?
Al 04/07/13 11:16, En/na Dennis Poon ha escrit: With RS-485 hardware you can - and supposedly need to - do half-duplex with output enable, if your hardware provides this. After days of google search, I am afraid the bcm2835, the Soc of Raspberry Pi (the hardware I have to use) does not provide this hardware support :-( It states that it does not even support interrupt. Polling is the only way for events :-( If that's true, you could use an usb to rs485 adapter, most of those do the tx/rx switching automatically, so you just see a normal serial port (of course you'll have to manage the high level protocol yourself). I've mostly used them in 422 mode (4 wires/full duplex) but I used one of them once in rs485 mode (2 wires/half duplex). IIRC the brand was VSCom. Bye -- Luca ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] How to use UART of ARM platforms (e.g. Raspberry Pi ) through free Pascal?
thanks. I am not using the fpc email as it seems off topic. May I know the exact brand and model number of the adapter you used? I have an ATEN usb-to-serial cable (UC-232A) but I am not sure how to connect its serial pins to rs-485 's DIFFERENTIAL LINES and how to set that adapter into half-duplex translation mode. Dennis Luca Olivetti wrote: Al 04/07/13 11:16, En/na Dennis Poon ha escrit: With RS-485 hardware you can - and supposedly need to - do half-duplex with output enable, if your hardware provides this. After days of google search, I am afraid the bcm2835, the Soc of Raspberry Pi (the hardware I have to use) does not provide this hardware support :-( It states that it does not even support interrupt. Polling is the only way for events :-( If that's true, you could use an usb to rs485 adapter, most of those do the tx/rx switching automatically, so you just see a normal serial port (of course you'll have to manage the high level protocol yourself). I've mostly used them in 422 mode (4 wires/full duplex) but I used one of them once in rs485 mode (2 wires/half duplex). IIRC the brand was VSCom. Bye ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] How to use UART of ARM platforms (e.g. Raspberry Pi ) through free Pascal?
On 07/04/2013 12:08 PM, Dennis Poon wrote: I have an ATEN usb-to-serial cable (UC-232A) b That is not suitable. There are dedicate RS485 Adapters (many of those also support RS422 mode (differential full duplex) ). But the problem might be that they don't come with a Linux driver for ARM. -Michael ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] How to use UART of ARM platforms (e.g. Raspberry Pi ) through free Pascal?
Al 04/07/13 12:08, En/na Dennis Poon ha escrit: thanks. I am not using the fpc email as it seems off topic. May I know the exact brand and model number of the adapter you used? I don't know the exact model, but it is one of these http://vscom.de/1_1_09.htm however there are other brands that should work equally well I have an ATEN usb-to-serial cable (UC-232A) but I am not sure how to connect its serial pins to rs-485 's DIFFERENTIAL LINES and how to set that adapter into half-duplex translation mode. That's not good: you'll need a level converter (which will probably cost more than an usb to rs485 adapter) *and* use one of the control pin to commute between tx/rx, the problem is, when you transmit you don't know when the last bit exits the serial port, so you cannot reliably control the switching pin. An usb-485 adapter usually does it all by itself at the right time. Bye -- Luca ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] How to use UART of ARM platforms (e.g. Raspberry Pi ) through free Pascal?
Al 04/07/13 12:24, En/na Michael Schnell ha escrit: But the problem might be that they don't come with a Linux driver for ARM. Since the driver for prolific/ftdi usb to serial bridge (which is the one these adapters use) is in the kernel since, like, forever, it will work with any architecture. Bye -- Luca ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] How to use UART of ARM platforms (e.g. Raspberry Pi ) through free Pascal?
On 07/04/2013 05:08 AM, Dennis Poon wrote: thanks. I am not using the fpc email as it seems off topic. May I know the exact brand and model number of the adapter you used? I have an ATEN usb-to-serial cable (UC-232A) but I am not sure how to connect its serial pins to rs-485 's DIFFERENTIAL LINES and how to set that adapter into half-duplex translation mode. Dennis My favorite is the USB-RS485-WE-1800-BT made by FTDI. It is sold by many companies: http://www.ftdichip.com/Products/Cables/USBRS485.htm It supports 24000 baud which many other adapters don't. I've only used it under Windows but as it is made by FTDI I would think using it under Linux should be no problem. www.CtrlTerm.com has Synapse and SynaSer code that should work on the RPi (for serial and TCP/IP communication) as I did test that recently. Please let me know if you have any problems and I will do further testing on my RPi. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] How to use UART of ARM platforms (e.g. Raspberry Pi ) through free Pascal?
On 07/04/2013 03:55 PM, Luca Olivetti wrote: Since the driver for prolific/ftdi usb to serial bridge (which is the one these adapters use) is in the kernel since, like, forever, it will work with any architecture. I do know that there is a standard for how many USB-to-serial adapters work. But in fact I also know that some don't adhere to that. In fact I only did a research on that for Windows. Here the standard driver by Microsoft works with many adapters, but it lacks some features (e.g. allowing the software to handle DSR/DTR). But e.g. the WT devices come with their own driver that can do this. I don't know whether they also can work with the standard driver, if DSR/DTR are not necessary. -Michael ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] How to use UART of ARM platforms (e.g. Raspberry Pi ) through free Pascal?
Synaser: http://synapse.ararat.cz/doc/help/synaser.html -Michael ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] How to use UART of ARM platforms (e.g. Raspberry Pi ) through free Pascal?
On 07/03/2013 07:18 AM, Dennis Poon wrote: Anyone has some sample codes or links to share on this? So far, I only found this: http://code.google.com/p/fprpbm/source/browse/#svn%2Ftrunk%2Fexamples%2Fminiuart%253Fstate%253Dclosed http://www.ctrlterm.com/ ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] How to use UART of ARM platforms (e.g. Raspberry Pi ) through free Pascal?
Michael,
I used the synapser.pas unit but the compiler choked at line 232 at the
identifier 'B50', 'B576000' not found.
Any idea ?
Dennis
Rates: array[0..MaxRates, 0..1] of cardinal =
(
(0, B0),
(50, B50),
(75, B75),
(110, B110),
(134, B134),
(150, B150),
(200, B200),
(300, B300),
(600, B600),
(1200, B1200),
(1800, B1800),
(2400, B2400),
(4800, B4800),
(9600, B9600),
(19200, B19200),
(38400, B38400),
(57600, B57600),
(115200, B115200),
(230400, B230400)
{$IFNDEF DARWIN}
,(460800, B460800)
{$IFDEF UNIX}
,(50, B50),
(576000, B576000),
(921600, B921600),
(100, B100),
(1152000, B1152000),
(150, B150),
(200, B200),
(250, B250),
(300, B300),
(350, B350),
(400, B400)
{$ENDIF}
{$ENDIF}
Michael Schnell wrote:
Synaser:
http://synapse.ararat.cz/doc/help/synaser.html
-Michael
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Re: [fpc-pascal] How to use UART of ARM platforms (e.g. Raspberry Pi ) through free Pascal?
After some studying, synaser.pas seems to deal with com port instead of the low level UART interface. Can you give me some pointer on directly using UART? I need to implement half-duplex using UART for rs-485 protocol. Thanks. Dennis Michael Schnell wrote: Synaser: http://synapse.ararat.cz/doc/help/synaser.html -Michael ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3345 / Virus Database: 3204/6458 - Release Date: 07/02/13 ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
