Difference between revisions of "User:JanosA"

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My hobby is programming embedded systems and creating my own small electronic boards.
 
My hobby is programming embedded systems and creating my own small electronic boards.
  
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=== Skills ===
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== Skills ==
 
* Assembly programming: PIC 8bit family
 
* Assembly programming: PIC 8bit family
 
* C programming: PIC 8bit / PIC32MX family, Linux
 
* C programming: PIC 8bit / PIC32MX family, Linux
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* IP networking
 
* IP networking
  
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=== My ArmadeuS plans (APF28 based) ===
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== My ArmadeuS plans (APF28 based) ==
 
* Creating an universal home automation hardware for my friends, with easy programming in perl or PHP. :)
 
* Creating an universal home automation hardware for my friends, with easy programming in perl or PHP. :)
 
* Datacenter temperature monitoring, with RS-485 and OneWire communications.
 
* Datacenter temperature monitoring, with RS-485 and OneWire communications.
 
* Data logger for Saia Sbus based intelligent power meters.
 
* Data logger for Saia Sbus based intelligent power meters.
  
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=== Currently I working on: ===
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== My works comitted to ArmadeuS project ==
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* RS485 support for driver: mxs-auart.c (APF28 2.6.35.3+ kernel)
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* [[RS-485]] for APF28/iMX28 mxs-auart and busybox stty patch
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* Next will be: Integrate and test the Linux kernel's one wire (w1) driver with APF28.
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* [[OneWire GPIO bus Master]] for APF28DEV
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== RS485 ==
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Informations and mini HOWTOs for my APF28/iMX28 mxs-auart and busybox stty patches.
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=== Linux stty ===
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* Setup APF28 serial port for RS485 communication:
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<pre class=apf>
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# stty -F /dev/ttySP0 raw
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# stty -F /dev/ttySP0 -echo -echoe -echok
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# stty -F /dev/ttySP0 rs485
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</pre>
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* Set extra delays for TXEN/RTS signaling before and after the transmitted packet (in microseconds):
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<pre class=apf>
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# stty -F /dev/ttySP0 rs485delaybefore 100
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# stty -F /dev/ttySP0 rs485delayafter 100
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</pre>
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* To get current RS485 parameters. (If the port device supports the RS485 options you will see the last two lines)
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<pre class=apf>
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# stty -F /dev/ttySP0
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speed 9600 baud; line = 0;
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intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ^D; eol = <undef>;
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eol2 = <undef>; swtch = <undef>; start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R;
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werase = ^W; lnext = ^V; flush = ^O; min = 1; time = 0;
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-brkint -imaxbel
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rs485 -rs485rtsonsend -rs485rtsaftersend -rs485rxduringtx
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rs485delaybefore = 100; rs485delayafter = 100; rs485delaylastchartx = 1250;
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</pre>
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Please note:
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* You can't set the "rs485delaylastchartx" parameter, it's calculated automatically from the baudrate.
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Special notes for the APF28/iMX28 mxs-auart driver:
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* All delays are in microseconds.
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* The "rs485delaylastchartx" parameter is not used in DMA mode.
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* The parameters: "rs485rtsonsend" "rs485rtsaftersend" "rs485rxduringtx" are not used.
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* If the RS485 mode is turned on, it will override (turn off) the RTS/CTS hardware flow settings of the uart, don't care what is configured.
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=== C code ===
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* The RS485 mode can be turned on with ioctl calls from C code, here is the example:
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<source lang="C">
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#include <stdio.h>
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#include <fcntl.h>
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#include <linux/ioctl.h>
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#include <linux/serial.h>
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#include <asm-generic/ioctls.h> /* TIOCGRS485 + TIOCSRS485 ioctl definitions */
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int main(void) {
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        struct serial_rs485 rs485conf;
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        int fd = open ("/dev/ttySP0", O_RDWR);
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        if (fd < 0) {
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                printf("Error: Can't open: /dev/ttySP0\n");
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        }
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        /* Don't forget to read first the current state of the RS485 options with ioctl.
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            If You don't do this, You will destroy the rs485conf.delay_rts_last_char_tx
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            parameter which is automatically calculated by the driver when You opens the
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            port device. */
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        if (ioctl (fd, TIOCGRS485, &rs485conf) < 0) {
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                printf("Error: TIOCGRS485 ioctl not supported.\n");
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        }
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        /* Enable RS485 mode: */
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        rs485conf.flags |= SER_RS485_ENABLED;
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        /* Set rts/txen delay before send, if needed: (in microseconds) */
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        rs485conf.delay_rts_before_send = 0;
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        /* Set rts/txen delay after send, if needed: (in microseconds) */
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        rs485conf.delay_rts_after_send = 0;
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        if (ioctl (fd, TIOCSRS485, &rs485conf) < 0) {
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                printf("Error: TIOCSRS485 ioctl not supported.\n");
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        }
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        fcntl(fd, F_SETFL, 0);
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        int n = write(fd, "ABC\r\n", 5);
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        if (n < 0) {
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                /* Error handling */
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        }
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        if (close (fd) < 0) {
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                printf("Error: Can't close: /dev/ttySP0\n");
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        }
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}
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</source>
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=== Hardware Notes ===
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* The RS485 Transmit Enable (TXEN) output will be the RTS pin of the uart.
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* The TXEN/RTS output is _active low_, it must be inverted to use it with the popular RS485 transceiver ICs.
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* When the u-boot runs and the board start to boot, the RTS pin works as input, please add a pullup resistor to this pin before the inverter, to prevent RS485 bus lockups.
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Latest revision as of 14:39, 19 May 2013

About Me

I am IP Network and Datacenter engineer, currently I'm working for an Internet Service Provider in Hungary.

My hobby is programming embedded systems and creating my own small electronic boards.

Skills

  • Assembly programming: PIC 8bit family
  • C programming: PIC 8bit / PIC32MX family, Linux
  • Perl, PHP, Javascript, Html programming with MySQL
  • Linux system administration
  • RS-232/485 serial communications: Ascii, Modbus, Saia Sbus, etc.
  • IP networking

My ArmadeuS plans (APF28 based)

  • Creating an universal home automation hardware for my friends, with easy programming in perl or PHP. :)
  • Datacenter temperature monitoring, with RS-485 and OneWire communications.
  • Data logger for Saia Sbus based intelligent power meters.

My works comitted to ArmadeuS project

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