AP_HAL: add chargen UARTDriver example

libraries/AP_HAL/examples/UART_chargen/UART_chargen.cpp

@@ -0,0 +1,98 @@
+/*
+  simple test of UART interfaces
+
+  on an UP2's hardware serial:
+  DEVICE=/dev/ttyS5
+  socat -,escape=0x0f $DEVICE,rawer,crnl,b4000000 | dd status=progress >/dev/null
+  n.b. socat corrupts the data; screen(1) does not
+
+
+  @ 4Mbaud:
+
+  unbuffered:
+  21526016 bytes (22 MB, 21 MiB) copied, 55.5364 s, 388 kB/s
+
+  buffered:
+  1702912 bytes (1.7 MB, 1.6 MiB) copied, 36.3764 s, 46.8 kB/s
+
+ */
+
+#include <AP_HAL/AP_HAL.h>
+
+#include <AP_BoardConfig/AP_BoardConfig.h>
+
+#define UNBUFFERED_WRITES 1
+#define FLOW_CONTROL_ENABLED 1
+
+void setup();
+void loop();
+
+const AP_HAL::HAL& hal = AP_HAL::get_HAL();
+
+static const uint32_t baud = 4000000;
+
+AP_HAL::UARTDriver *uart;
+
+uint8_t buffer[16384];
+uint16_t buflen = 0;
+
+void setup(void)
+{
+    hal.scheduler->delay(1000); //Ensure that the uartA can be initialized
+
+#if CONFIG_HAL_BOARD == HAL_BOARD_LINUX
+    uart = hal.uartA;  //  console
+#endif
+    // uart = hal.uartB;   // 1st GPS
+#if CONFIG_HAL_BOARD == HAL_BOARD_CHIBIOS
+    uart = hal.uartC;  // telemetry 1
+#endif
+    // uart = hal.uartD;  // telemetry 2
+    // uart = hal.uartE;  // 2nd GPS
+
+
+    if (uart == nullptr) {
+        AP_HAL::panic("bad uart");
+    }
+
+#if UNBUFFERED_WRITES
+    uart->set_unbuffered_writes(true);
+#endif
+
+    uart->begin(baud);
+
+#if FLOW_CONTROL_ENABLED
+    uart->set_flow_control(AP_HAL::UARTDriver::flow_control::FLOW_CONTROL_ENABLE);
+#endif
+
+    // populate chargen buffer
+    for (uint8_t line=0; line<95; line++) {
+        for (uint8_t i=0; i<72; i++) {
+            uint8_t c = ' ' + line + i;
+            if (c >= ' ' + 72) {
+                c -= 72;
+            }
+            buffer[buflen++] = c;
+        }
+        buffer[buflen++] = '\r';
+        buffer[buflen++] = '\n';
+    }
+}
+
+void loop(void)
+{
+    uint16_t offset = 0;
+    while (offset < buflen) {
+        uint16_t to_write = buflen-offset;
+        const ssize_t ret = uart->write(&buffer[offset], to_write);
+        if (ret > 0) {
+            offset += ret;
+        }
+#if !UNBUFFERED_WRITES
+        // give the uart thread time to move data from buffer to uart:
+        hal.scheduler->delay(1);
+#endif
+    }
+}
+
+AP_HAL_MAIN();

libraries/AP_HAL/examples/UART_chargen/wscript

@@ -0,0 +1,7 @@
+#!/usr/bin/env python
+# encoding: utf-8
+
+def build(bld):
+    bld.ap_example(
+        use='ap',
+    )