AP_HAL_ChibiOS: get the last time when the tx write buffer got emptied

ArduPilot · Feb 13, 2024 · 252d6cc · 252d6cc
1 parent ea4617b
commit 252d6cc
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diff --git a/libraries/AP_HAL_ChibiOS/UARTDriver.cpp b/libraries/AP_HAL_ChibiOS/UARTDriver.cpp
@@ -146,6 +146,11 @@ void UARTDriver::uart_thread()
         if (_tx_initialised && ((mask & EVT_TRANSMIT_DATA_READY) || need_tick || (hd_tx_active && (mask & EVT_TRANSMIT_END)))) {
             _tx_timer_tick();
         }
+
+        // record the time when a half-duplex TX buffer got emptied
+        if (_tx_initialised && hd_tx_active && (mask & EVT_TRANSMIT_END) && _writebuf.is_empty()) {
+            _last_write_completed_us = now;
+        }
     }
 }
 #pragma GCC diagnostic pop

diff --git a/libraries/AP_HAL_ChibiOS/UARTDriver.h b/libraries/AP_HAL_ChibiOS/UARTDriver.h
@@ -131,6 +131,13 @@ class ChibiOS::UARTDriver : public AP_HAL::UARTDriver {
      */
     bool is_dma_enabled() const override { return rx_dma_enabled && tx_dma_enabled; }
 
+    // get the last time when the tx write buffer got emptied
+#if CH_CFG_USE_EVENTS == TRUE
+    uint32_t get_last_tx_empty_us() const override { return ((tx_dma_enabled || half_duplex) && _writebuf.is_empty()) ? _last_write_completed_us : 0; }
+#else
+    uint32_t get_last_tx_empty_us() const override { return (tx_dma_enabled && _writebuf.is_empty()) ? _last_write_completed_us : 0; }
+#endif
+
 private:
     const SerialDef &sdef;
     bool rx_dma_enabled;