Changes between Version 1 and Version 2 of serial

Timestamp:

10/22/2017 06:24:15 AM (7 years ago)

Author:

Chris Lang

Comment:

--

serial

@@ -18 +18 @@
 
 The following table describes the various on-board UARTs for standard Gateworks products. Please consult the board specific hardware user manual for additional details:
-||= Family =||= Board =||= Device =||= Function         =||
-|| Avila    || GW2347  || ttyS0    || console: 3.3V TTL JTAG J2 / RS232 J5   ||
-||          ||         || ttyS1    || UART: RS232 J3                         || 
-||          || GW2348  || ttyS0    || console: 3.3V TTL JTAG J7 / RS232 J13  ||
-||          ||         || ttyS1    || UART: RS232 J6                         ||
-||          || GW2355  || ttyS0    || console: 3.3V TTL JTAG J3 / RS232 J5   ||
-||          ||         || ttyS1    || GPS                                    ||
-||          || GW2357  || ttyS0    || console: 3.3V TTL JTAG J2 / RS232 J6   ||
-||          ||         || ttyS1    || UART: RS232 J36                        ||
-|| Cambria  || GW2350  || ttyS0    || console: 3.3V TTL JTAG J1/J10          ||
-||          ||         || ttyS1    || GPS                                    ||
-||          ||         || ttyS2    || RS485 J6                               ||
-||          || GW2358  || ttyS0    || console: 3.3V TTL JTAG J10 / RS232 J17 ||
-||          ||         || ttyS1    || GPS                                    ||
-||          ||         || ttyS2    || RS485 J3                               ||
-|| Rincon   || GW2361  || ttyS0    || console: 3.3V TTL JTAG J2              ||
-||          ||         || ttyS1    || RS232 J7                               ||
-||          ||         || ttyS2    || RS485 J6                               ||
-|| Laguna   || GW2380/2/3 || ttyS0    || console: 3.3V TTL JTAG J2 / 3.3V TTL J4 ||                            
-||          ||         || ttyS1    || GPS                                        ||
-||          ||         || ttyS2    || UART: 3.3V TTL J8                          ||
-||          || GW2387  || ttyS0    || console: 3.3V TTL JTAG J3/J7 / RS232 J13   ||
-||          ||         || ttyS1    || RS232 J13 / 3.3V TTL J7                    ||
-||          ||         || ttyS2    || GPS                                        ||
-||          || GW2388  || ttyS0    || console: 3.3V TTL JTAG J8 / RS232 J21      ||
-||          ||         || ttyS1    || RS232 J21                                  ||
-||          ||         || ttyS2    || GPS                                        ||
-||          || GW2391  || ttyS0    || console: 3.3V TTL JTAG J1 / RS232 J15      ||
-||          ||         || ttyS1    || RS232 J15                                  ||
-||          ||         || ttyS2    || GPS                                        ||
-|| Ventana  || GW51xx  || ttymxc0  || GPS ||
-||          ||         || ttymxc1  || console: 3.3V TTL JTAG J10/J11 ||
-||          ||         || ttymxc4  || TTL J11 ||
-||          || GW52xx  || ttymxc0  || RS485/CAN/TTL J12 / RS232 J10 ||
-||          ||         || ttymxc1  || console: 3.3V TTL JTAG J14 / RS232 J10 ||
-||          ||         || ttymxc4  || GPS ||
-||          || GW53xx  || ttymxc0  || RS485/CAN/TTL J11 / RS232 J12 ||
-||          ||         || ttymxc1  || console: 3.3V TTL JTAG J14 / RS232 J12 ||
-||          ||         || ttymxc4  || GPS ||
-||          || GW54xx  || ttymxc0  || RS485 J13 ||
-||          ||         || ttymxc1  || console: 3.3V TTL JTAG J17 / RS232 J15 ||
-||          ||         || ttymxc4  || GPS ||
-||          || GW551x  || ttymxc1  || console: exp 3.3V TTL J3             ||
-||          ||         || ttymxc2  || exp 3.3V TTL J3           ||
-||          || GW552x  || ttymxc1  || console: 3.3V TTL JTAG J7 ||
-||          ||         || ttymxc2  || exp 3.3V TTL J5           ||
-||          ||         || ttymxc4  || exp 3.3V TTL J5           ||
-||          || GW553x  || ttymxc1  || console: 3.3V TTL JTAG J11 ||
-||          ||         || ttymxc2  || exp 3.3V TTL JTAG J10 ||
-||          ||         || ttymxc3  || GPS ||
-||          ||         || ttymxc4  || exp 3.3V TTL JTAG J10 ||
-||          || GW16111 || ttymxc1  || console: 3.3V TTL JTAG J8 / RS232 J16 / RS485 J20 ||
-||          ||         || ttymxc2  || RS232 J16 ||
+||= Family =||= Board =||= HW Dev =|| SW Dev =||= Function         =||
+|| Avila    || GW2347  || UART0    || ttyS0    || console: 3.3V TTL JTAG J2 / RS232 J5   ||
+||          ||         || UART1    || ttyS1    || UART: RS232 J3                         || 
+||          || GW2348  || UART0    || ttyS0    || console: 3.3V TTL JTAG J7 / RS232 J13  ||
+||          ||         || UART1    || ttyS1    || UART: RS232 J6                         ||
+||          || GW2355  || UART0    || ttyS0    || console: 3.3V TTL JTAG J3 / RS232 J5   ||
+||          ||         || UART1    || ttyS1    || GPS                                    ||
+||          || GW2357  || UART0    || ttyS0    || console: 3.3V TTL JTAG J2 / RS232 J6   ||
+||          ||         || UART1    || ttyS1    || UART: RS232 J36                        ||
+|| Cambria  || GW2350  || UART0    || ttyS0    || console: 3.3V TTL JTAG J1/J10          ||
+||          ||         || UART1    || ttyS1    || GPS                                    ||
+||          ||         || UART2    || ttyS2    || RS485 J6                               ||
+||          || GW2358  || UART0    || ttyS0    || console: 3.3V TTL JTAG J10 / RS232 J17 ||
+||          ||         || UART1    || ttyS1    || GPS                                    ||
+||          ||         || UART2    || ttyS2    || RS485 J3                               ||
+|| Rincon   || GW2361  || UART0    || ttyS0    || console: 3.3V TTL JTAG J2              ||
+||          ||         || UART1    || ttyS1    || RS232 J7                               ||
+||          ||         || UART2    || ttyS2    || RS485 J6                               ||
+|| Laguna   || GW2380/2/3 || UART0    || ttyS0    || console: 3.3V TTL JTAG J2 / 3.3V TTL J4 ||                            
+||          ||         || UART1    || ttyS1    || GPS                                        ||
+||          ||         || UART2    || ttyS2    || UART: 3.3V TTL J8                          ||
+||          || GW2387  || UART0    || ttyS0    || console: 3.3V TTL JTAG J3/J7 / RS232 J13   ||
+||          ||         || UART1    || ttyS1    || RS232 J13 / 3.3V TTL J7                    ||
+||          ||         || UART2    || ttyS2    || GPS                                        ||
+||          || GW2388  || UART0    || ttyS0    || console: 3.3V TTL JTAG J8 / RS232 J21      ||
+||          ||         || UART1    || ttyS1    || RS232 J21                                  ||
+||          ||         || UART2    || ttyS2    || GPS                                        ||
+||          || GW2391  || UART0    || ttyS0    || console: 3.3V TTL JTAG J1 / RS232 J15      ||
+||          ||         || UART1    || ttyS1    || RS232 J15                                  ||
+||          ||         || UART2    || ttyS2    || GPS                                        ||
+|| Ventana  || GW51xx  || UART1    || ttymxc0  || GPS ||
+||          ||         || UART2    || ttymxc1  || console: 3.3V TTL JTAG J10/J11 ||
+||          ||         || UART5    || ttymxc4  || TTL J11 ||
+||          || GW52xx  || UART1    || ttymxc0  || RS485/CAN/TTL J12 / RS232 J10 ||
+||          ||         || UART2    || ttymxc1  || console: 3.3V TTL JTAG J14 / RS232 J10 ||
+||          ||         || UART5    || ttymxc4  || GPS ||
+||          || GW53xx  || UART1    || ttymxc0  || RS485/CAN/TTL J11 / RS232 J12 ||
+||          ||         || UART2    || ttymxc1  || console: 3.3V TTL JTAG J14 / RS232 J12 ||
+||          ||         || UART5    || ttymxc4  || GPS ||
+||          || GW54xx  || UART1    || ttymxc0  || RS485 J13 / RS232 J15 ||
+||          ||         || UART2    || ttymxc1  || console: 3.3V TTL JTAG J17 / RS232 J15 ||
+||          ||         || UART5    || ttymxc4  || GPS ||
+||          || GW551x  || UART2    || ttymxc1  || console: exp 3.3V TTL J3             ||
+||          ||         || UART3    || ttymxc2  || exp 3.3V TTL J3           ||
+||          || GW552x  || UART2    || ttymxc1  || console: 3.3V TTL JTAG J7 ||
+||          ||         || UART3    || ttymxc2  || exp 3.3V TTL J5           ||
+||          ||         || UART5    || ttymxc4  || exp 3.3V TTL J5           ||
+||          || GW553x  || UART2    || ttymxc1  || console: 3.3V TTL JTAG J11 ||
+||          ||         || UART3    || ttymxc2  || exp 3.3V TTL JTAG J10 ||
+||          ||         || UART4    || ttymxc3  || GPS ||
+||          ||         || UART5    || ttymxc4  || exp 3.3V TTL JTAG J10 ||
+||          || GW16111 || UART2    || ttymxc1  || console: 3.3V TTL JTAG J8 / RS232 J16 / RS485 J20 ||
+||          ||         || UART3    || ttymxc2  || RS232 J16 ||
+
 
 
@@ -93 +94 @@
 
 == Serial Port Types (DCE vs DTE) ==
-The Data Communication Equipment (DCE) (Typically used on a Gateworks board) pin assignments permit direct connection to a standard Data Terminal Equipment (DTE) PC running terminal emulation software.
+The Data Communication Equipment (DCE) pin assignments permit direct connection to a standard Data Terminal Equipment (DTE) PC running terminal emulation software. The inputs and outputs are swapped between DCE and DTE. Please pay careful attention to the connector pinout of any UART from the board's hardware user manual, specifically the TX/RX/RTS/CTS pin's direction (input vs output) to ensure proper interconnect with off-board equipment.
 
 In certain scenarios, a null modem cable may be needed [http://en.wikipedia.org/wiki/Null_modem Null Modem Information]
@@ -134 +135 @@
 
 
+[=#flowcontrol]
+== Hardware Flow Control ==
+A few Gateworks products that provide TTL level and/or RS232 serial can optionally provide hardware flow control via RTS# and CTS# pins. In this configuration. All Gateworks products present serial from the Data Terminal Equipment (DTE) perspective where TX and RTS are outputs, and RX and CTS are inputs with one exception:
+ * Ventana UART's are in DCE mode by default however TX is still an output and RX is an input. Therefore Ventana UART's with flow control are pinned out as follows:
+  - TX (output)
+  - RX (input)
+  - RTS (input)
+  - CTS (output)
+
+
 [=#rs323]
 == RS232 ==
@@ -168 +179 @@
         -g              Print in stty-readable form
         [SETTING]       See manpage
-
+}}}
+
+Set the baud rate, example shown below for 115200:
+{{{
 root@OpenWrt:/# stty -F /dev/ttyS1 115200
+}}}
+
+'''Also''' Verify Flow Control: (adjust below example to exact application)
+{{{
+stty -crtscts -F /dev/ttyS1
 }}}
 
@@ -190 +209 @@
 
 Troubleshooting:
- * make sure you are either not using hardware/software flow control, or in the case that you do have hardware flow control (CTS/RTS or DTR/DSR) they are properly connected.
+ * make sure you are either not using hardware/software flow control, or in the case that you do have hardware flow control (CTS/RTS or DTR/DSR) they are properly connected.[#Flowcontrol See Link Here]
  * use a null-modem if needed (DTE vs DCE)
  * make sure both ends are RS232 compliant (as opposed to TTL level logic)
@@ -225 +244 @@
  * implement a protocol such that multiple masters know when it is there turn to transmit
 
-RS485 Networks also require termination. Most Gateworks boards which have RS485 have on-board 4.75Kohm pulls and an optional on-board 121ohm load termination resistor.
-
 In a typical scenario you may have two devices on an RS485 half-duplex bus, NodeA and NodeB and a conversation would look like this:
  1. NodeA enables its transmitter, sends out a request packet, then disables its transmitter and waits for a response
@@ -233 +250 @@
 
 The following table and sections below provides per-board details of RS485:
-||= Family  =||= Board        =||= TXEN =||= Termination =||= Notes =|| 
-|| Cambria   || GW235x         || DTR    || optional      || use tcdrain() and TIOCMBIC/TIOCMBIS ioctl ||
-||                 ||
-|| Rincon    || GW2361         || RTS    || off-board     || use tcdrain() and TIOCMBIC/TIOCMBIS ioctl ||
-||                 ||
-|| Laguna    || GW2380+GW16067 || gpio3  || optional      || use tcdrain() and userspace /sys/class/gpio/gpio3 ||
-||                 ||
-|| Ventana   || GW551x+GW16111 || gpio19  || optional     || see [#ventana-rs485 below] || 
-|| Ventana   || GW52xx '''(optional)''' || gpio193 || optional     || TIOCSRS485 support ||
-|| Ventana   || GW53xx '''(optional)'''         || gpio193 || optional     || TIOCSRS485 support ||
-|| Ventana   || GW54xx '''(optional)'''         || gpio193 || optional     || TIOCSRS485 support ||
+||= Family  =||= Board                 =||= TXEN  =||= Transceiver =||= Termination =||= Fail-Safe Bias =||= Notes =|| 
+|| Cambria   || GW235x '''(optional)''' || DTR     || [http://dev.gateworks.com/datasheets/MAX3483-MAX3491.pdf MAX3485] || optional      || optional  || use tcdrain() and TIOCMBIC/TIOCMBIS ioctl ||
+|| ||
+|| Rincon    || GW2361 '''(optional)''' || RTS     || [http://dev.gateworks.com/datasheets/MAX3483-MAX3491.pdf MAX3485] || off-board     || off-board || use tcdrain() and TIOCMBIC/TIOCMBIS ioctl ||
+|| ||
+|| Laguna    || GW238x+GW16067          || gpio3   || [http://dev.gateworks.com/datasheets/MAX3483-MAX3491.pdf MAX3485] || optional      || 4.75k pull up/down || use tcdrain() and userspace /sys/class/gpio/gpio3 ||
+|| ||
+|| Ventana   || GW551x+GW16111          || gpio19  || [http://dev.gateworks.com/datasheets/MAX14840E-MAX14841E.pdf MAX14840] || optional      || 4.75k pull up/down || see [#ventana-rs485 ventana RS485 below] || 
+|| Ventana   || GW52xx '''(optional)''' || gpio193 || [http://dev.gateworks.com/datasheets/MAX14840E-MAX14841E.pdf MAX14840] || optional      || optional || TIOCSRS485 support ||
+|| Ventana   || GW53xx '''(optional)''' || gpio193 || [http://dev.gateworks.com/datasheets/MAX14840E-MAX14841E.pdf MAX14840] || optional      || optional || TIOCSRS485 support ||
+|| Ventana   || GW54xx '''(optional)''' || gpio193 || [http://dev.gateworks.com/datasheets/MAX14840E-MAX14841E.pdf MAX14840] || optional      || optional || TIOCSRS485 support ||
 
 Note that if a driver supports TIOCSRS485 (in other words it handles the assertion/de-assertion of TXEN in the driver) this is preferred over using tcdrain() to determine when the FIFO is empty as tcdrain() can have considerable latency at small transmit sizes.
@@ -251 +268 @@
  * https://en.wikipedia.org/wiki/RS-485
 
+
+[=#rs485-termination]
+=== RS485 Termination ===
+As a general rule, termination resistors should be placed at both far ends of the RS485 network. Without termination resistors reflections of fast driver edges can cause data corruption. Termination resistors also reduce electrical noise sensitivity due to lower impedance. The value of each termination resistor should be equal to the cable characteristic impedance (typically 120 ohms for twisted pairs).
+
+Some boards with RS485 capability may have transceivers with specific fail-safe features within the transceiver however optional on-board termination resistors typically exist as well and it is the responsibility of the system designer to determine where termination needs to go and what values should be used. In general, gateworks boards with RS485 transceivers have an optional resistor for termination that can be loaded with a customer specified value. Contact sales@gateworks.com via e-mail for more information.
+
+References:
+ * [https://www.maximintegrated.com/en/app-notes/index.mvp/id/763 Maxium Tutorial 763 - Guidelines for Proper Wiring of an RS-485 Network]
+ * https://en.wikipedia.org/wiki/RS-485
+
+
+[=#rs485-failsafebias]
+=== RS485 Failsafe Bias Resistors ===
+When inputs are between -200mV and +200mV the receiver output is 'undefined'. There are four common fault conditions that result in this undefined receiver output that can cause erroneous data:
+ * All transmitters in a system are not driving
+ * The receiver is not connected to the cable
+ * The cable has an open
+ * The cable has a short
+
+Fail-safe biasing is used to keep the receiver's output in a defined state when one of these conditions occur. The biasing consists of a pull-up resistor on the noninverting line and a pull-down resistor on the inverting line. With proper biasing, the receiver will output a valid high when any one of the fault conditions occur. These fail-safe bias resistors should be placed at the receiver end of the transmission line.
+
+Some boards with RS485 capability may have on-board termination resistor options and it is the responsibility of the system designer to determine where termination needs to go and what values should be used. In general, gateworks boards with RS485 transceivers have an optional resistor for termination that can be loaded with a customer specified value. Contact sales@gateworks.com via e-mail for more information.
+
+on-board failsafe bias resistors 4.75Kohm pulls and an optional on-board 121ohm load termination resistor.
+
+References:
+ * [https://www.maximintegrated.com/en/app-notes/index.mvp/id/763 Maxium Tutorial 763 - Guidelines for Proper Wiring of an RS-485 Network]
+ * https://en.wikipedia.org/wiki/RS-485
 
 [=#cambria-rs485]
@@ -258 +304 @@
  * MAX3485 transceiver
  * TXEN connected to DTR
- * '''optional termination
+ * '''optional on-board termination resistor'''
+ * '''optional on-board fail-safe bias resistors'''
 
 By 'optional' this means the baseboard design supports this, but it is not loaded on standard product therefore would be a Gateworks Special. Contact sales@gateworks.com if interested to see if a configuration already exists.
@@ -281 +328 @@
  * MAX3485 transceiver
  * TXEN connected to gpio3
- * '''optional termination (R5)
- * 4.75k pull-up on D+, 4.75k pull-down on D- (bus defaults to logic 1 - never idle)
+ * '''optional on-board termination resistor (R5)'''
+ * '''on-board fail-safe bias resistors (R3/R7) by default are 4.75k pull-up on D+, 4.75k pull-down on D-''' (bus defaults to logic 1 - never idle)
 
 By 'optional' this means the baseboard design supports this, but it is not loaded on standard product therefore would be a Gateworks Special. Contact sales@gateworks.com if interested to see if a configuration already exists.
@@ -295 +342 @@
  * MAX14840 transceiver
  * TXEN connected to gpio193
- * '''optional termination
- * '''optional D+ pull-up and D- pull-down
+ * '''optional on-board termination resistor'''
+ * '''optional on-board fail-safe resistors (D+ pull-up and D- pull-down)'''
 
 By 'optional' this means the baseboard design supports this, but it is not loaded on standard product therefore would be a Gateworks Special. Contact sales@gateworks.com if interested to see if a configuration already exists.
@@ -311 +358 @@
   - '''TXD drive mode''' - jumpers placed on '''J10:2-3''' and '''J10:7-8''' will cause the transceiver to be enabled only when TX is asserted. Because there are 4.75k pull's on D+/D- the bus is never 'idle'. This is useful for multi-master scenarios but could pose issues with fast/large busses if the 4.75pull's are not strong enough to switch the signals quick enough.
   - '''DIO-drive mode''' - jumpers placed on '''J10:2-3''' and '''J10:7-8''' will cause the transceiver to be enabled only when IMX_DIO1 (gpio19) is asserted high. This is useful for fast/large busses where the TXD drive mode doesn't provide fast enough switching. If using this mode you either need to manage the assertion/de-assertion of gpio19 in usersapce or modify the GW551x device-tree to configure rs485-txen for TIOCSRS485 support by adding '''fsl,rs485-gpio-txen = <&gpio1 19 GPIO_ACTIVE_HIGH>;''' to the uart2 device-tree node in arch/arm/boot/dts/imx6qdl-gw551x.dtsi
- * 121ohm termination can be enabled by placing a jumper on '''J10:9-10'''
- * 4.75k pull-up on D+, 4.75k pull-down on D- (bus defaults to logic 1 - never idle)
+ * 121ohm termination (R38) is loaded and can be enabled by placing a jumper on '''J10:9-10'''
+ * 4.75k pull-up on D+, 4.75k pull-down on D- fail-safe bias resistors are loaded (R37/R40) (bus defaults to logic 1 - never idle)
 
 
@@ -326 +373 @@
 #include <termios.h>
 #include <time.h>
+#include <unistd.h>
 #include <fcntl.h>
 #include <sys/ioctl.h>
 #include <linux/serial.h>
+
+#ifndef TIOCSRS485
+#define TIOCSRS485        0x542F
+#endif
 
 /** main function
@@ -337 +389 @@
         int fd, sz, rz, bytes;
         speed_t speed;
-        const char *baud, *mode, *dev, *txen = NULL;
+        const char *baud, *mode, *dev;
         int timeout = 2; // time in seconds to wait for response
-        char *msg;
+        char *msg = NULL;
         char buf[8192];
         time_t start;
 
-        if (argc < 5) {
+        if (argc < 4) {
                 fprintf(stderr,
-                        "usage: %s <device> <baud> <mode> <message> [<txen>]\n",
+                        "usage: %s <device> <baud> <mode> [<message>]\n",
                         argv[0]);
                 exit(1);
@@ -353 +405 @@
         baud = argv[2];
         mode = argv[3];
-        msg = argv[4];
-        if (argc > 5)
-                txen = argv[5];
+        if (argc > 4)
+                msg = argv[4];
 
         // open device
@@ -425 +476 @@
 
         // configure rs485
-        if (txen) {
+        {
                 struct serial_rs485 rs485;
 
-                printf("enabling rs485 for %s txen\n", txen);
+                printf("enabling rs485 via TIOCSRS485\n");
                 memset(&rs485, 0, sizeof(rs485));
                 rs485.flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND;
@@ -438 +489 @@
         tcflush(fd, TCIOFLUSH);
 
-        sz = atoi(msg);
-        if (!sz) {
-                sprintf(buf, "%s", msg);
-                sz = strlen(msg) + 1;
-        }
-        printf("transmitting %d bytes...\n", sz);
-        if (write(fd, buf, sz) != sz)
-                perror("tx");
+        // transmit data
+        if (msg) {
+                printf("sending...\n");
+                if (strcmp("STDIN", msg) == 0) {
+                        while (1) {
+                                sz = read(0, buf, sizeof(buf));
+                                printf("transmitting %d bytes...\n", sz);
+                                if (write(fd, buf, sz) != sz) {
+                                        perror("tx");
+                                        break;
+                                }
+                        }
+                } else {
+                        sz = strlen(msg) + 1;
+                        printf("transmitting %d bytes...\n", sz);
+                        if (write(fd, msg, sz) != sz)
+                                perror("tx");
+                }
+        }
 
         // receive data
         printf("reading...\n"); 
-        bytes = 0;
-        memset(buf, 0, sizeof(buf));
-        start = time(NULL);
         while (1) {
-                rz = read(fd, buf + bytes, sz - bytes);
+                memset(buf, 0, sizeof(buf));
+                rz = read(fd, buf, sizeof(buf) - 1);
                 if (rz < 0) {
                         perror("read failed");
                         break;
                 }
-                bytes += rz;
-
-                if (bytes >= sz)
-                        break;
-
-                if ((int)(time(NULL) - start) >= timeout) {
-                        printf("timeout\n");
-                        break;
-                }
-
-                usleep(100000);
-        }
-        printf("received %d bytes in %ds\n", bytes, (int)(time(NULL) - start));
-        if (!atoi(msg))
-                printf("%s\n", buf);
+                if (rz == 0)
+                        continue;
+                printf("rx %d(%d): '%s'\n", rz, strlen(buf), buf);
+        }
 
         // restore terminal state