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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 ===
| | == 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) ===
| | == 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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| | | == My works comitted to ArmadeuS project == |
| | | * [[RS-485]] for APF28/iMX28 mxs-auart and busybox stty patch |
| | | * [[OneWire GPIO bus Master]] for APF28DEV |
| == RS485 == | |
| 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. (Only used by atmel_serial.c and crisv10.c drivers)
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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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| == OneWire ==
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| Informations and mini HOWTOs for my APF28DEV OneWire patch.
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| | |
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| === Software installation ===
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| * Recompile your Linux kernel with OneWire GPIO bus master (and some slave device) support. | |
| <pre class="host">
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| $ make linux-menuconfig
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| </pre>
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| <pre class="config">
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| Device Drivers --->
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| <*> Dallas's 1-wire support --->
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| 1-wire Bus Masters --->
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| <*> GPIO 1-wire busmaster
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| 1-wire Slaves --->
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| <*> Thermal family implementation
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| </pre>
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| <pre class="host">
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| $ make
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| </pre>
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| * Reflash your Linux kernel
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| | |
| | |
| === Hardware Notes ===
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| * Connect the OneWire slave directly to the APF28_DEV board J9 connector:
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| * Vcc 3.3V is pin 1 on J9 connector
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| * DQ is pin 31 on J9 (LCD_D18 / GPIO 1_18)
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| * GND is pin 39 on J9
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| * Add an 1.2k pullup resistor between Vcc and DQ
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| | |
| | |
| === How it works ===
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| The OneWire bus master driver every 10 seconds scan the bus for new slave devices.
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| | |
| Each detected OneWire slave device have a sub-directory with it's unique ID in "/sys/devices/w1 bus master".
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| | |
| The sub-directory format is <2 digit family ID>-<12 digit unique ID>.
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| <pre class=apf>
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| # ls -la /sys/devices/w1\ bus\ master/
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| total 0
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| drwxr-xr-x 4 root root 0 Jan 1 01:06 .
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| drwxr-xr-x 6 root root 0 Jan 1 01:05 ..
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| drwxr-xr-x 3 root root 0 Jan 1 01:06 28-000001e68904
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| lrwxrwxrwx 1 root root 0 Jan 1 01:07 driver -> ../../bus/w1/drivers/w1_master_driver
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| drwxr-xr-x 2 root root 0 Jan 1 01:07 power
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| lrwxrwxrwx 1 root root 0 Jan 1 01:07 subsystem -> ../../bus/w1
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| -rw-r--r-- 1 root root 4096 Jan 1 01:07 uevent
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| -rw-rw-rw- 1 root root 4096 Jan 1 01:07 w1_master_add
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| -r--r--r-- 1 root root 4096 Jan 1 01:07 w1_master_attempts
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| -r--r--r-- 1 root root 4096 Jan 1 01:07 w1_master_max_slave_count
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| -r--r--r-- 1 root root 4096 Jan 1 01:07 w1_master_name
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| -r--r--r-- 1 root root 4096 Jan 1 01:07 w1_master_pointer
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| -rw-rw-rw- 1 root root 4096 Jan 1 01:07 w1_master_pullup
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| -rw-rw-rw- 1 root root 4096 Jan 1 01:07 w1_master_remove
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| -rw-rw-rw- 1 root root 4096 Jan 1 01:07 w1_master_search
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| -r--r--r-- 1 root root 4096 Jan 1 01:07 w1_master_slave_count
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| -r--r--r-- 1 root root 4096 Jan 1 01:07 w1_master_slaves
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| -r--r--r-- 1 root root 4096 Jan 1 01:07 w1_master_timeout
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| </pre>
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| You can list the detected slaves from this files:
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| <pre class=apf>
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| # cat /sys/devices/w1\ bus\ master/w1_master_slave_count
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| 1
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| # cat /sys/devices/w1\ bus\ master/w1_master_slaves
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| 28-000001e68904
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| </pre>
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| Let's read the temperature: (The 28-xxx family is a DS18B20 temperature sensor in this example.)
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| <pre class=apf>
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| # cat /sys/devices/w1\ bus\ master/28-000001e68904/w1_slave
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| dd 01 4b 46 7f ff 03 10 1e : crc=1e YES
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| dd 01 4b 46 7f ff 03 10 1e t=29812
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| </pre>
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| The t=29812 means, the temperature is: 29.812°C
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