Prepare sensor hub HAL functions for BNO085 driver.

Note: RESET/IRQ/BOOTN GPIOs will need to be controlled separately.

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "sh2"]
+	path = sh2
+	url = https://github.com/pika-spark/pika-spark-sh2

CMakeLists.txt

@@ -3,14 +3,19 @@ cmake_minimum_required(VERSION 3.15)
 ##########################################################################
 project("pika-spark-bno085-driver")
 ##########################################################################
+add_subdirectory(sh2)
+##########################################################################
 add_executable(${PROJECT_NAME} 
   main.cpp
+  bno085.cpp
   spi.cpp
 )
 ##########################################################################
 if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
   target_compile_options(${PROJECT_NAME} PRIVATE -Wall -Werror -Wextra -Wpedantic)
 endif()
 ##########################################################################
+target_link_libraries(${PROJECT_NAME} pika-spark-sh2)
+##########################################################################
 target_compile_features(${PROJECT_NAME} PUBLIC cxx_std_17)
 ##########################################################################

bno085.cpp

@@ -0,0 +1,132 @@
+/**
+ * This software is distributed under the terms of the MIT License.
+ * Copyright (c) 2023 LXRobotics.
+ * Author: Alexander Entinger <alexander.entinger@lxrobotics.com>
+ * Contributors: https://github.com/107-systems/pika-spark-bno085-driver/graphs/contributors.
+ */
+
+/**************************************************************************************
+ * INCLUDE
+ **************************************************************************************/
+
+#include "bno085.h"
+
+#include <cstring>
+
+/**************************************************************************************
+ * PRIVATE FUNCTION DECLARATIONS
+ **************************************************************************************/
+
+static int      priv_sh2_hal_open     (sh2_Hal_t * self);
+static void     priv_sh2_hal_close    (sh2_Hal_t * self);
+static int      priv_sh2_hal_read     (sh2_Hal_t * self, uint8_t * pBuffer, unsigned len, uint32_t * t_us);
+static int      priv_sh2_hal_write    (sh2_Hal_t * self, uint8_t * pBuffer, unsigned len);
+static uint32_t priv_sh2_hal_getTimeUs(sh2_Hal_t * self);
+
+/**************************************************************************************
+ * CTOR/DTOR
+ **************************************************************************************/
+
+BNO085::BNO085(std::shared_ptr<SPI> const spi)
+: _spi{spi}
+, _start{std::chrono::steady_clock::now()}
+{
+  _sh2_hal.user_reference = reinterpret_cast<void *>(this);
+
+  reset();
+  init();
+}
+
+/**************************************************************************************
+ * PUBLIC MEMBER FUNCTIONS
+ **************************************************************************************/
+
+int BNO085::sh2_hal_read(uint8_t * pBuffer, unsigned len, uint32_t * /* t_us */)
+{
+  /* Read the sensor hub header. */
+  uint8_t       sh_hdr_rx_buf[4] = {0};
+  uint8_t const sh_hdr_tx_buf[4] = {0};
+
+  if (!_spi->transfer(sh_hdr_tx_buf, sh_hdr_rx_buf, sizeof(sh_hdr_tx_buf)))
+    return 0;
+
+  /* Determine packet size (mask out continuous bit). */
+  uint16_t const packet_size =
+    (static_cast<uint16_t>(sh_hdr_rx_buf[0]) | static_cast<uint16_t>(sh_hdr_rx_buf[1]) << 8) & 0x7FFF;
+
+  size_t const bytes_to_read = std::min(static_cast<size_t>(packet_size), static_cast<size_t>(len));
+
+  /* Ensure that we only transmit zero's. */
+  memset(pBuffer, 0, bytes_to_read);
+
+  /* Transmit zero's and read from the device. */
+  if (!_spi->transfer(pBuffer, pBuffer, bytes_to_read))
+    return 0;
+
+  return bytes_to_read;
+}
+
+int BNO085::sh2_hal_write(uint8_t * pBuffer, unsigned len)
+{
+  if (!_spi->transfer(pBuffer, pBuffer, len))
+    return 0;
+
+  return len;
+}
+
+uint32_t BNO085::sh2_hal_getTimeUs()
+{
+  auto const now = std::chrono::steady_clock::now();
+  auto const uptime = (now - _start);
+  return std::chrono::duration_cast<std::chrono::microseconds>(uptime).count();
+}
+
+/**************************************************************************************
+ * PRIVATE MEMBER FUNCTIONS
+ **************************************************************************************/
+
+void BNO085::reset()
+{
+  /* TODO. */
+}
+
+void BNO085::init()
+{
+  _sh2_hal.open      = priv_sh2_hal_open;
+  _sh2_hal.close     = priv_sh2_hal_close;
+  _sh2_hal.read      = priv_sh2_hal_read;
+  _sh2_hal.write     = priv_sh2_hal_write;
+  _sh2_hal.getTimeUs = priv_sh2_hal_getTimeUs;
+}
+
+/**************************************************************************************
+ * PRIVATE FUNCTION DEFINITIONS
+ **************************************************************************************/
+
+int priv_sh2_hal_open(sh2_Hal_t * /* self */)
+{
+  return 0;
+}
+
+void priv_sh2_hal_close(sh2_Hal_t * /* self */)
+{
+  /* Do nothing. */
+}
+
+int priv_sh2_hal_read(sh2_Hal_t * self, uint8_t * pBuffer, unsigned len, uint32_t * t_us)
+{
+  BNO085 * this_ptr = reinterpret_cast<BNO085 *>(self->user_reference);
+  return this_ptr->sh2_hal_read(pBuffer, len, t_us);
+}
+
+int priv_sh2_hal_write(sh2_Hal_t * self, uint8_t * pBuffer, unsigned len)
+{
+  BNO085 * this_ptr = reinterpret_cast<BNO085 *>(self->user_reference);
+  return this_ptr->sh2_hal_write(pBuffer, len);
+}
+
+uint32_t priv_sh2_hal_getTimeUs(sh2_Hal_t * self)
+{
+  BNO085 * this_ptr = reinterpret_cast<BNO085 *>(self->user_reference);
+  return this_ptr->sh2_hal_getTimeUs();
+}

bno085.h

@@ -0,0 +1,44 @@
+/**
+ * This software is distributed under the terms of the MIT License.
+ * Copyright (c) 2023 LXRobotics.
+ * Author: Alexander Entinger <alexander.entinger@lxrobotics.com>
+ * Contributors: https://github.com/107-systems/pika-spark-bno085-driver/graphs/contributors.
+ */
+
+#pragma once
+
+/**************************************************************************************
+ * INCLUDE
+ **************************************************************************************/
+
+#include <chrono>
+#include <memory>
+
+#include <sh2.h>
+
+#include "spi.h"
+
+/**************************************************************************************
+ * CLASS DECLARATION
+ **************************************************************************************/
+
+class BNO085
+{
+public:
+  BNO085(std::shared_ptr<SPI> const spi);
+
+  /* Do not publicly use those functions.
+   * They are used for the sensor hub HAL.
+   */
+  int      sh2_hal_read     (uint8_t * pBuffer, unsigned len, uint32_t * t_us);
+  int      sh2_hal_write    (uint8_t * pBuffer, unsigned len);
+  uint32_t sh2_hal_getTimeUs();
+
+private:
+  std::shared_ptr<SPI> const _spi;
+  std::chrono::steady_clock::time_point const _start;
+  sh2_Hal_t _sh2_hal;
+
+  void reset();
+  void init();
+};

main.cpp

@@ -12,10 +12,12 @@
 #include <stdexcept>
 
 #include "spi.h"
+#include "bno085.h"
 
 int main(int /* argc */, char ** /* argv */) try
 {
-  auto spi = std::make_shared<SPI>("/dev/spidev1.0", SPI_MODE_0, 8, 1000000);
+  auto spi = std::make_shared<SPI>("/dev/spidev1.0", SPI_MODE_3, 8, 1*1000*1000UL);
+  auto bno085 = std::make_shared<BNO085>(spi);
   return EXIT_SUCCESS;
 }
 catch (std::runtime_error const & err)