Added option for fast SBUS (200000 baud)

bolderflight · Sep 29, 2022 · 50b7fc9 · 50b7fc9
1 parent b457d85
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,5 +1,8 @@
 # Changelog
 
+## v8.1.0
+- Added option for fast SBUS (200000 baud)
+
 ## v8.0.1
 - Enabling ESP32 to use non-inverted SBUS
 

diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -12,7 +12,7 @@ if (DEFINED MCU)
   set(CMAKE_TOOLCHAIN_FILE "${mcu_support_SOURCE_DIR}/cmake/cortex.cmake")
   # Project information
   project(Sbus
-    VERSION 8.0.0
+    VERSION 8.1.0
     DESCRIPTION "SBUS encoder and decoder"
     LANGUAGES C CXX
   )

diff --git a/README.md b/README.md
@@ -23,6 +23,8 @@ The SBUS protocol uses an inverted serial logic with a baud rate of 100000, 8 da
 
 Note that lost frame is indicated when a frame is lost between the transmitter and receiver. Failsafe activation typically requires that many frames are lost in a row and indicates that the receiver has moved into failsafe mode. Packets are sent approximately every 10 ms or 20 ms, depending on the system configuration.
 
+A variation on SBUS called "Fast SBUS" has started to be used. This uses a baudrate of 200000 and a quicker update rate.
+
 **Note on CH17 and CH18:** Channel 17 and channel 18 are digital on/off channels. These are not universally available on all SBUS receivers and servos.
 
 FrSky receivers will output a range of 172 - 1811 with channels set to a range of -100% to +100%. Using extended limits of -150% to +150% outputs a range of 0 to 2047, which is the maximum range acheivable with 11 bits of data.
@@ -112,8 +114,12 @@ bfs::SbusRx sbus(&Serial1);
 bfs::SbusRx sbus(&Serial1, false);
 ```
 
+**SbusRx(HardwareSerial &ast;bus, const bool inv, const bool fast)** Same as the constructor above, but enables selecting the fast SBUS baudrate (200000) if *fast* is true.
+
 **(ESP32 ONLY) SbusRx(HardwareSerial &ast;bus, const int8_t rxpin, const int8_t txpin, const bool inv)** Creates an *SbusRx* object. A pointer to the *Serial* object corresponding to the serial port used is passed along with the RX pin number (*rxpin*), TX pin number (*txpin*), and whether inverted serial is used (*inv*). If *inv* is true, the signal is the standard inverted SBUS, otherwise it is non-inverted SBUS.
 
+**(ESP32 ONLY) SbusRx(HardwareSerial &ast;bus, const int8_t rxpin, const int8_t txpin, const bool inv, const bool fast)** Same as the constructor above, but enables selecting the fast SBUS baudrate (200000) if *fast* is true.
+
 **void Begin()** Initializes SBUS communication.
 
 ```C++

diff --git a/library.properties b/library.properties
@@ -1,5 +1,5 @@
 name=Bolder Flight Systems SBUS
-version=8.0.1
+version=8.1.0
 author=Brian Taylor <[email protected]>
 maintainer=Brian Taylor <[email protected]>
 sentence=Library for communicating with SBUS receivers and servos.

diff --git a/src/sbus.cpp b/src/sbus.cpp
@@ -35,13 +35,18 @@
 namespace bfs {
 
 void SbusRx::Begin() {
+  if (fast_) {
+    baud_ = 200000;
+  } else {
+    baud_ = 100000;
+  }
   /* Start the bus */
   /* Teensy 3.0 || Teensy 3.1/3.2 */
   #if defined(__MK20DX128__) || defined(__MK20DX256__)
   if (inv_) {
-    uart_->begin(BAUD_, SERIAL_8E1_RXINV_TXINV);
+    uart_->begin(baud_, SERIAL_8E1_RXINV_TXINV);
   } else {
-    uart_->begin(BAUD_, SERIAL_8E1);
+    uart_->begin(baud_, SERIAL_8E1);
   }
   /*
   * Teensy 3.5 || Teensy 3.6 ||
@@ -52,24 +57,24 @@ void SbusRx::Begin() {
         defined(__MKL26Z64__)  || defined(__IMXRT1062__) || \
         defined(__IMXRT1052__)
   if (inv_){
-    uart_->begin(BAUD_, SERIAL_8E2_RXINV_TXINV);
+    uart_->begin(baud_, SERIAL_8E2_RXINV_TXINV);
   } else {
-    uart_->begin(BAUD_, SERIAL_8E2);
+    uart_->begin(baud_, SERIAL_8E2);
   }
   /* STM32L4 */
   #elif defined(STM32L496xx) || defined(STM32L476xx) || \
         defined(STM32L433xx) || defined(STM32L432xx)
   if (inv_) {
-    uart_->begin(BAUD_, SERIAL_8E2 | 0xC000ul);
+    uart_->begin(baud_, SERIAL_8E2 | 0xC000ul);
   } else {
-    uart_->begin(BAUD_, SERIAL_8E2);
+    uart_->begin(baud_, SERIAL_8E2);
   }
   /* ESP32 */
   #elif defined(ESP32)
-  uart_->begin(BAUD_, SERIAL_8E2, rxpin_, txpin_, inv_);
+  uart_->begin(baud_, SERIAL_8E2, rxpin_, txpin_, inv_);
   /* Everything else, with a hardware inverter */
   #else
-  uart_->begin(BAUD_, SERIAL_8E2);
+  uart_->begin(baud_, SERIAL_8E2);
   #endif
   /* flush the bus */
   uart_->flush();
@@ -174,13 +179,18 @@ namespace {
 #endif
 
 void SbusTx::Begin() {
+  if (fast_) {
+    baud_ = 200000;
+  } else {
+    baud_ = 100000;
+  }
   /* Start the bus */
   /* Teensy 3.0 || Teensy 3.1/3.2 */
   #if defined(__MK20DX128__) || defined(__MK20DX256__)
   if (inv_) {
-    uart_->begin(BAUD_, SERIAL_8E1_RXINV_TXINV);
+    uart_->begin(baud_, SERIAL_8E1_RXINV_TXINV);
   } else {
-    uart_->begin(BAUD_, SERIAL_8E1);
+    uart_->begin(baud_, SERIAL_8E1);
   }
   /*
   * Teensy 3.5 || Teensy 3.6 ||
@@ -191,24 +201,24 @@ void SbusTx::Begin() {
         defined(__MKL26Z64__)  || defined(__IMXRT1062__) || \
         defined(__IMXRT1052__)
   if (inv_){
-    uart_->begin(BAUD_, SERIAL_8E2_RXINV_TXINV);
+    uart_->begin(baud_, SERIAL_8E2_RXINV_TXINV);
   } else {
-    uart_->begin(BAUD_, SERIAL_8E2);
+    uart_->begin(baud_, SERIAL_8E2);
   }
   /* STM32L4 */
   #elif defined(STM32L496xx) || defined(STM32L476xx) || \
         defined(STM32L433xx) || defined(STM32L432xx)
   if (inv_) {
-    uart_->begin(BAUD_, SERIAL_8E2 | 0xC000ul);
+    uart_->begin(baud_, SERIAL_8E2 | 0xC000ul);
   } else {
-    uart_->begin(BAUD_, SERIAL_8E2);
+    uart_->begin(baud_, SERIAL_8E2);
   }
   /* ESP32 */
   #elif defined(ESP32)
-  uart_->begin(BAUD_, SERIAL_8E2, rxpin_, txpin_, inv_);
+  uart_->begin(baud_, SERIAL_8E2, rxpin_, txpin_, inv_);
   /* Everything else, with a hardware inverter */
   #else
-  uart_->begin(BAUD_, SERIAL_8E2);
+  uart_->begin(baud_, SERIAL_8E2);
   #endif
 }
 

diff --git a/src/sbus.h b/src/sbus.h
@@ -50,9 +50,16 @@ class SbusRx {
   SbusRx(HardwareSerial *bus, const int8_t rxpin, const int8_t txpin,
          const bool inv) : uart_(bus), inv_(inv), rxpin_(rxpin), txpin_(txpin)
          {}
+  SbusRx(HardwareSerial *bus, const int8_t rxpin, const int8_t txpin,
+         const bool inv, const bool fast) : uart_(bus), inv_(inv),
+                                            rxpin_(rxpin), txpin_(txpin),
+                                            fast_(fast) {}
   #else
   explicit SbusRx(HardwareSerial *bus) : uart_(bus) {}
   SbusRx(HardwareSerial *bus, const bool inv) : uart_(bus), inv_(inv) {}
+  SbusRx(HardwareSerial *bus, const bool inv, const bool fast) : uart_(bus),
+                                                                 inv_(inv),
+                                                                 fast_(fast) {}
   #endif
   void Begin();
   bool Read();
@@ -62,10 +69,11 @@ class SbusRx {
   /* Communication */
   HardwareSerial *uart_;
   bool inv_ = true;
+  bool fast_ = false;
   #if defined(ESP32)
   int8_t rxpin_, txpin_;
   #endif
-  static constexpr uint32_t BAUD_ = 100000;
+  int32_t baud_ = 100000;
   /* Message len */
   static constexpr int8_t PAYLOAD_LEN_ = 23;
   static constexpr int8_t HEADER_LEN_ = 1;
@@ -97,9 +105,16 @@ class SbusTx {
   SbusTx(HardwareSerial *bus, const int8_t rxpin, const int8_t txpin,
          const bool inv) : uart_(bus), inv_(inv), rxpin_(rxpin), txpin_(txpin)
          {}
+  SbusTx(HardwareSerial *bus, const int8_t rxpin, const int8_t txpin,
+         const bool inv, const bool fast) : uart_(bus), inv_(inv),
+                                            rxpin_(rxpin), txpin_(txpin),
+                                            fast_(fast) {}
   #else
   explicit SbusTx(HardwareSerial *bus) : uart_(bus) {}
   SbusTx(HardwareSerial *bus, const bool inv) : uart_(bus), inv_(inv) {}
+  SbusTx(HardwareSerial *bus, const bool inv, const bool fast) : uart_(bus),
+                                                                 inv_(inv),
+                                                                 fast_(fast) {}
   #endif
   void Begin();
   void Write();
@@ -110,10 +125,11 @@ class SbusTx {
   /* Communication */
   HardwareSerial *uart_;
   bool inv_ = true;
+  bool fast_ = false;
   #if defined(ESP32)
   int8_t rxpin_, txpin_;
   #endif
-  static constexpr uint32_t BAUD_ = 100000;
+  int32_t baud_ = 100000;
   /* Message len */
   static constexpr int8_t BUF_LEN_ = 25;
   /* SBUS message defs */