RC_Channel: added RC_UART example

useful for UART -> ESCs

libraries/RC_Channel/examples/RC_UART/Makefile

@@ -0,0 +1,2 @@
+BOARD	=	mega
+include ../../../../mk/apm.mk

libraries/RC_Channel/examples/RC_UART/RC_UART.cpp

@@ -0,0 +1,131 @@
+/*
+  take RC channels in from UART and put out as PWM
+ */
+
+#include <AP_HAL/AP_HAL.h>
+#include <RC_Channel/RC_Channel.h>
+#include <GCS_MAVLink/include/mavlink/v1.0/checksum.h>
+
+const AP_HAL::HAL& hal = AP_HAL::get_HAL();
+
+#define NUM_CHANNELS 4
+#define ESC_MAGIC 0xF7
+#define RC_SPEED 490
+#define UART uartE
+
+class RC_UART : public AP_HAL::HAL::Callbacks {
+public:
+    // HAL::Callbacks implementation.
+    void setup() override;
+    void loop() override;
+
+private:
+    uint8_t read_wait(void);
+    uint8_t enable_mask;
+    const uint32_t baudrate = 115200;
+    uint32_t counter;
+
+    RC_Channel rc_1{0};
+    RC_Channel rc_2{1};
+    RC_Channel rc_3{2};
+    RC_Channel rc_4{3};
+    RC_Channel *rc = &rc_1;
+};
+
+void RC_UART::setup()
+{
+    hal.scheduler->delay(1000);
+    hal.console->println("RC_UART starting");
+    hal.UART->begin(baudrate, 512, 512);
+    hal.rcout->set_freq(0xFF, RC_SPEED);
+}
+
+uint8_t RC_UART::read_wait(void)
+{
+    while (true) {
+        int16_t c = hal.UART->read();
+        if (c != -1) {
+            // hal.console->printf("c=0x%02x\n", (unsigned)c);
+            return c;
+        }
+        hal.scheduler->delay_microseconds(100);
+    }
+}
+
+void RC_UART::loop()
+{
+    union {
+        uint16_t period[NUM_CHANNELS];
+        uint8_t bytes[NUM_CHANNELS*2];
+    } u;
+
+    // wait for magic
+    while (true) {
+        uint8_t c = read_wait();
+        if (c == ESC_MAGIC) break;
+        // hal.console->printf("c=0x%02x\n", (unsigned)c);
+    }
+
+    uint8_t nbytes=0;
+    // wait for periods
+    while (nbytes < NUM_CHANNELS*2) {
+        u.bytes[nbytes++] = read_wait();
+    }
+
+    // and CRC
+    union {
+        uint8_t crc[2];
+        uint16_t crc16;
+    } u2;
+    u2.crc[0] = read_wait();
+    u2.crc[1] = read_wait();
+    uint16_t crc2 = crc_calculate(u.bytes, NUM_CHANNELS*2);
+    if (crc2 != u2.crc16) {
+        hal.console->printf("bad CRC 0x%04x should be 0x%04x\n", (unsigned)crc2, (unsigned)u2.crc16);
+        return;
+    }
+
+    // and output
+    for (uint8_t i=0; i<NUM_CHANNELS; i++) {
+        if (u.period[i] == 0) {
+            continue;
+        }
+        if (!(enable_mask & 1U<<i)) {
+            if (enable_mask == 0) {
+                hal.rcout->force_safety_off();
+            }
+            rc[i].enable_out();
+            enable_mask |= 1U<<i;
+        }
+        rc[i].radio_out = u.period[i];
+        rc[i].output();
+    }
+
+    // report periods to console for debug
+    counter++;
+    if (counter % 100 == 0) {
+        hal.console->printf("%4u %4u %4u %4u\n",
+                            (unsigned)u.period[0],
+                            (unsigned)u.period[1],
+                            (unsigned)u.period[2],
+                            (unsigned)u.period[3]);
+    }
+
+    // every 10th frame give an RCInput frame if possible
+    if (counter % 10 == 0) {
+        struct PACKED {
+            uint8_t magic = 0xf6;
+            uint16_t rcin[8];
+            uint16_t crc;
+        } rcin;
+        if (hal.rcin->new_input() && hal.rcin->read(rcin.rcin, 8) == 8) {
+            rcin.crc = crc_calculate((uint8_t*)&rcin.rcin[0], 16);
+            hal.UART->write((uint8_t*)&rcin, sizeof(rcin));
+        }
+    }
+}
+
+RC_UART rc_uart;
+
+AP_HAL_MAIN_CALLBACKS(&rc_uart);
+

libraries/RC_Channel/examples/RC_UART/make.inc

@@ -0,0 +1,26 @@
+LIBRARIES += AP_ADC
+LIBRARIES += AP_AHRS
+LIBRARIES += AP_Airspeed
+LIBRARIES += AP_Baro
+LIBRARIES += AP_Common
+LIBRARIES += AP_Compass
+LIBRARIES += AP_Declination
+LIBRARIES += AP_GPS
+LIBRARIES += AP_InertialSensor
+LIBRARIES += AP_Math
+LIBRARIES += AP_Mission
+LIBRARIES += AP_NavEKF
+LIBRARIES += AP_Notify
+LIBRARIES += AP_Param
+LIBRARIES += AP_Progmem
+LIBRARIES += AP_Rally
+LIBRARIES += AP_RangeFinder
+LIBRARIES += AP_Scheduler
+LIBRARIES += AP_Terrain
+LIBRARIES += AP_Vehicle
+LIBRARIES += DataFlash
+LIBRARIES += Filter
+LIBRARIES += GCS_MAVLink
+LIBRARIES += RC_Channel
+LIBRARIES += StorageManager
+LIBRARIES += AP_OpticalFlow

libraries/RC_Channel/examples/RC_UART/wscript

@@ -0,0 +1,10 @@
+#!/usr/bin/env python
+# encoding: utf-8
+
+import ardupilotwaf
+
+def build(bld):
+    ardupilotwaf.program(
+        bld,
+        use='ap',
+    )