Using std::array for passing around SBUS data and commands

bolderflight · Dec 17, 2021 · ddd6984 · ddd6984
1 parent 8fe02a0
commit ddd6984
Show file tree

Hide file tree

Showing 8 changed files with 69 additions and 64 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,5 +1,8 @@
 # Changelog
 
+## v7.0.0
+- Using std::array for passing around SBUS data and commands
+
 ## v6.0.3
 - Cleaned up folder structure after merge
 - Pulling in mcu-support repo for CMake builds

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 6.0.3
+    VERSION 7.0.0
     DESCRIPTION "SBUS encoder and decoder"
     LANGUAGES C CXX
   )

diff --git a/README.md b/README.md
@@ -3,9 +3,10 @@
 ![Bolder Flight Systems Logo](img/logo-words_75.png) &nbsp; &nbsp; ![Arduino Logo](img/arduino_logo_75.png)
 
 # Sbus
-This library communicates with SBUS receivers and servos and is compatible with Arduino and CMake build systems.
+This library communicates with SBUS receivers and servos and is compatible with Arduino ARM and CMake build systems.
    * [License](LICENSE.md)
    * [Changelog](CHANGELOG.md)
+   * [Contributing guide](CONTRIBUTING.md)
 
 # Description
 SBUS is a bus protocol for receivers to send commands to servos. Unlike PWM, SBUS uses a bus architecture where a single serial line can be connected with up to 16 servos with each receiving a unique command.
@@ -20,7 +21,7 @@ The SBUS protocol uses an inverted serial logic with a baud rate of 100000, 8 da
       * Bit 3: failsafe activated (0x08)
    * Byte[24]: SBUS footer
 
-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. 
+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.
 
 **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.
 
@@ -50,6 +51,8 @@ Simply clone or download and extract the zipped library into your Arduino/librar
 #include "sbus.h"
 ```
 
+An example is located in *examples/arduino/sbus_example/sbus_example.ino*. This library is tested with Teensy 3.x, 4.x, and LC devices and should work with other ARM devices. It is **not** expected to work with AVR due to the use of std::array.
+
 ## CMake
 CMake is used to build this library, which is exported as a library target called *sbus*. The header is added as:
 
@@ -84,7 +87,7 @@ This class is used for receiving SBUS data from an SBUS capable receiver.
 **SbusRx(HardwareSerial &ast;bus)** Creates an SbusRx object. A pointer to the Serial object corresponding to the serial port used is passed. The RX pin of the serial port will receive SBUS packets.
 
 ```C++
-SbusRx sbus(&Serial1);
+bfs::SbusRx sbus(&Serial1);
 ```
 
 **void Begin()** Initializes SBUS communication.
@@ -105,17 +108,10 @@ if (sbus.Read()) {
 
 **static constexpr int8_t NUM_CH()** A constant defining the number of SBUS channels (i.e. 16), useful for defining arrays to read the data into.
 
-**int8_t ch(int16_t * const data, const int8_t len)** Copys the array of received channel data given a pointer to a destination, *data*, and length of the destination array *len*. Returns the number of channels copied on success or -1 on failure. Note that the maximum number of channels is the smaller of the *len* or *NUM_CH* (i.e. 16).
+**std::array<int16_t, NUM_SBUS_CH_> ch()** Returns an array of received channel data.
 
 ```C++
-int16_t rx_ch[bfs::SbusRx::NUM_CH];
-sbus.ch(rx_ch, bfs::SbusRx::NUM_CH);
-```
-
-**int16_t ch(const int8_t idx)** Returns received channel data given the channel index.
-
-```C++
-int16_t ch3_data = sbus.ch(3);
+std::array<int16_t, bfs::SbusRx::NUM_CH()> rx_ch = sbus.ch();
 ```
 
 **bool ch17()** Returns the value of channel 17.
@@ -148,7 +144,7 @@ This class is used for transmitting SBUS data to SBUS capable servos.
 **SbusTx(HardwareSerial &ast;bus)** Creates an SbusTx object. A pointer to the Serial object corresponding to the serial port used is passed. The TX pin of the serial port will transmit SBUS packets.
 
 ```C++
-SbusTx sbus(&Serial1);
+bfs::SbusTx sbus(&Serial1);
 ```
 
 **void Begin()** Initializes SBUS communication.
@@ -191,16 +187,40 @@ sbus.lost_frame(true);
 sbus.failsafe(true);
 ```
 
-**bool ch(const int8_t idx, const int16_t val)** Sets the channel data to be transmitted, given a channel index and corresponding value. Returns true on success and false on failure.
+**void ch(const std::array<int16_t, NUM_SBUS_CH_> &cmd)** Sets the channel data to be transmitted given an array of SBUS commands.
 
 ```C++
-/* Set channel 3 to a value of 1200 */
-sbus.ch(3, 1200);
+/* Set SBUS commands */
+std::array<int16_t, bfs::SbusTx::NUM_CH()> cmd;
+sbus.ch(cmd);
+```
+
+**bool ch17()** Returns the CH17 data to be transmitted.
+
+```C++
+bool ch17 = sbus.ch17();
+```
+
+**bool ch18()** Returns the CH18 data to be transmitted.
+
+```C++
+bool ch18 = sbus.ch18();
+```
+
+**bool lost_frame()** Returns the lost frame flag to be transmitted.
+
+```C++
+bool lost_frame = sbus.lost_frame();
+```
+
+**bool failsafe()** Returns the failsafe flag to be transmitted.
+
+```C++
+bool failsafe = sbus.failsafe();
 ```
 
-**int8_t ch(int16_t const * const data, const int8_t len)** Sets the channel data to be transmitted given a pointer to an array of commands, *data*, and the array length, *len*. Returns the number of channels copied on success or -1 on failure. Note that the maximum number of channels is the smaller of the *len* or *NUM_CH* (i.e. 16).
+**std::array<int16_t, NUM_SBUS_CH_> ch()** Returns the channel data to be transmitted.
 
 ```C++
-int16_t cmd[bfs::SbusTx::NUM_CH()];
-sbus.ch(cmd, bfs::SbusTx::NUM_CH());
+std::array<int16_t, bfs::SbusRx::NUM_CH()> rx_ch = sbus.ch();
 ```
diff --git a/examples/arduino/sbus_example/sbus_example.ino b/examples/arduino/sbus_example/sbus_example.ino
@@ -40,7 +40,7 @@ bfs::SbusRx sbus_rx(&Serial1);
 /* SbusTx object on Serial1 */
 bfs::SbusTx sbus_tx(&Serial1);
 /* Array for storing SBUS data */
-int16_t sbus_data[bfs::SbusRx::NUM_CH()];
+std::array<int16_t, bfs::SbusRx::NUM_CH()> sbus_data;
 
 void setup() {
   /* Serial to display the received data */
@@ -53,9 +53,10 @@ void setup() {
 
 void loop() {
   if (sbus_rx.Read()) {
+    /* Grab the received data */
+    sbus_data = sbus_rx.ch();
     /* Display the received data */
     for (int8_t i = 0; i < bfs::SbusRx::NUM_CH(); i++) {
-      sbus_data[i] = sbus_rx.ch(i);
       Serial.print(sbus_data[i]);
       Serial.print("\t");
     }
@@ -64,7 +65,7 @@ void loop() {
     Serial.print("\t");
     Serial.println(sbus_rx.failsafe());
     /* Set the SBUS TX data to the received data */
-    sbus_tx.ch(sbus_data, bfs::SbusRx::NUM_CH());
+    sbus_tx.ch(sbus_data);
     /* Write the data to the servos */
     sbus_tx.Write();
   }

diff --git a/examples/cmake/sbus_example.cc b/examples/cmake/sbus_example.cc
@@ -30,7 +30,7 @@ bfs::SbusRx sbus_rx(&Serial1);
 /* SBUS object, writing SBUS */
 bfs::SbusTx sbus_tx(&Serial1);
 /* Array for storing SBUS data */
-int16_t sbus_data[bfs::SbusRx::NUM_CH()];
+std::array<int16_t, bfs::SbusRx::NUM_CH()> sbus_data;
 
 int main() {
   /* Serial to display data */
@@ -41,9 +41,10 @@ int main() {
   sbus_tx.Begin();
   while (1) {
     if (sbus_rx.Read()) {
+      /* Grab the received data */
+      sbus_data = sbus_rx.ch();
       /* Display the received data */
       for (int8_t i = 0; i < bfs::SbusRx::NUM_CH(); i++) {
-        sbus_data[i] = sbus_rx.ch(i);
         Serial.print(sbus_data[i]);
         Serial.print("\t");
       }
@@ -52,7 +53,7 @@ int main() {
       Serial.print("\t");
       Serial.println(sbus_rx.failsafe());
       /* Set the SBUS TX data to the received data */
-      sbus_tx.ch(sbus_data, bfs::SbusRx::NUM_CH());
+      sbus_tx.ch(sbus_data);
       /* Write the data to the servos */
       sbus_tx.Write();
     }

diff --git a/library.properties b/library.properties
@@ -1,5 +1,5 @@
 name=Bolder Flight Systems SBUS
-version=6.0.3
+version=7.0.0
 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
@@ -27,9 +27,12 @@
 #if defined(ARDUINO)
 #include <Arduino.h>
 #else
-#include <algorithm>
 #include "core/core.h"
 #endif
+#include <cstddef>
+#include <cstdint>
+#include <cmath>
+#include <array>
 
 namespace bfs {
 
@@ -107,20 +110,6 @@ bool SbusRx::Read() {
   }
   return new_data_;
 }
-int8_t SbusRx::ch(int16_t * const data, const int8_t len) {
-  if (!data) {return -1;}
-  #if defined(ARDUINO)
-  int8_t cpy_len = min(NUM_SBUS_CH_, len);
-  #else
-  int8_t cpy_len = std::min(NUM_SBUS_CH_, len);
-  #endif
-  memcpy(data, ch_, cpy_len * sizeof(int16_t));
-  return cpy_len;
-}
-int16_t SbusRx::ch(const int8_t idx) {
-  if ((idx < 0) || (idx >= NUM_SBUS_CH_)) {return -1;}
-  return ch_[idx];
-}
 bool SbusRx::Parse() {
   /* Parse messages */
   while (uart_->available()) {
@@ -242,20 +231,5 @@ void SbusTx::Write() {
   uart_->write(buf_, sizeof(buf_));
   #endif
 }
-bool SbusTx::ch(const int8_t idx, const int16_t val) {
-  if ((idx < 0) || (idx >= NUM_SBUS_CH_)) {return false;}
-  ch_[idx] = val;
-  return true;
-}
-int8_t SbusTx::ch(int16_t const * const data, const int8_t len) {
-  if (!data) {return -1;}
-  #if defined(ARDUINO)
-  int8_t cpy_len = min(NUM_SBUS_CH_, len);
-  #else
-  int8_t cpy_len = std::min(NUM_SBUS_CH_, len);
-  #endif
-  memcpy(ch_, data, cpy_len * sizeof(int16_t));
-  return cpy_len;
-}
 
 }  // namespace bfs
diff --git a/src/sbus.h b/src/sbus.h
@@ -29,9 +29,12 @@
 #if defined(ARDUINO)
 #include <Arduino.h>
 #else
-#include <algorithm>
 #include "core/core.h"
 #endif
+#include <cstddef>
+#include <cstdint>
+#include <cmath>
+#include <array>
 
 namespace bfs {
 
@@ -59,7 +62,7 @@ class SbusRx {
   uint8_t buf_[BUF_LEN_];
   /* Data */
   bool new_data_;
-  int16_t ch_[NUM_SBUS_CH_];
+  std::array<int16_t, NUM_SBUS_CH_> ch_;
   bool failsafe_ = false, lost_frame_ = false, ch17_ = false, ch18_ = false;
   bool Parse();
 
@@ -72,8 +75,7 @@ class SbusRx {
   #endif
   bool Read();
   static constexpr int8_t NUM_CH() {return NUM_SBUS_CH_;}
-  int8_t ch(int16_t * const data, const int8_t len);
-  int16_t ch(const int8_t idx);
+  inline std::array<int16_t, NUM_SBUS_CH_> ch() const {return ch_;}
   inline bool failsafe() const {return failsafe_;}
   inline bool lost_frame() const {return lost_frame_;}
   inline bool ch17() const {return ch17_;}
@@ -98,7 +100,7 @@ class SbusTx {
   static constexpr uint8_t FAILSAFE_MASK_ = 0x08;
   /* Data */
   uint8_t buf_[BUF_LEN_];
-  int16_t ch_[NUM_SBUS_CH_];
+  std::array<int16_t, NUM_SBUS_CH_> ch_;
   bool failsafe_ = false, lost_frame_ = false, ch17_ = false, ch18_ = false;
 
  public:
@@ -114,8 +116,12 @@ class SbusTx {
   inline void lost_frame(const bool val) {lost_frame_ = val;}
   inline void ch17(const bool val) {ch17_ = val;}
   inline void ch18(const bool val) {ch18_ = val;}
-  bool ch(const int8_t idx, const int16_t val);
-  int8_t ch(int16_t const * const data, const int8_t len);
+  inline void ch(const std::array<int16_t, NUM_SBUS_CH_> &cmd) {ch_ = cmd;}
+  inline std::array<int16_t, NUM_SBUS_CH_> ch() const {return ch_;}
+  inline bool failsafe() const {return failsafe_;}
+  inline bool lost_frame() const {return lost_frame_;}
+  inline bool ch17() const {return ch17_;}
+  inline bool ch18() const {return ch18_;}
 };
 
 }  // namespace bfs