Proof of Concept mcp3008 reading

src/core/main.c

@@ -25,6 +25,8 @@
 // Source control information embedded at build-time
 #include "git.h"
 
+#include "mcp3008/mcp3008.h"
+
 extern void *__BUILD_INCLUDES_FLASHLOADER;
 
 #ifdef INCLUDES_FLASHLOADER
@@ -78,6 +80,24 @@ int main(void)
  pvRegisterFlashloaderTask();
 #endif
 
+ printf("HELLO, world!");
+
+ spi_inst_t *spi = spi0;
+
+ // TODO: fix schematic pinout (HW_SPI0)
+ spi_pinout_t pinout = {
+ .sck = 2,
+ .csn = 5,
+ .rx = 4,
+ .tx = 3,
+ };
+
+ spi_dual_inst inst = mcp3008_init_hardware(spi, 3600000, &pinout);
+ // true/false has no effect
+ uint16_t res = mcp3008_internal_do_adc(&inst, 1, false);
+
+ printf("\n%x", res);
+
  // TinyUSB demos call this after creating tasks.
  vTaskStartScheduler();
 

src/core/main.cmake

@@ -43,6 +43,7 @@ target_sources(${MAIN} PUBLIC
  ${CMAKE_CURRENT_LIST_DIR}/tinyusb-config/usb_descriptors.c
  ${CMAKE_CURRENT_LIST_DIR}/tasks/bulk.c
  ${CMAKE_CURRENT_LIST_DIR}/tasks/mcu_temperature.c
+ ${CMAKE_CURRENT_LIST_DIR}/mcp3008/mcp3008.c
  ${CMAKE_CURRENT_LIST_DIR}/config.h
  )
 
@@ -51,7 +52,7 @@ target_sources(${MAIN} PUBLIC
 # pico_malloc, pico_mem_ops - optimized versions of standard libraries.
 # memory management: FreeRTOS-Kernel-Heap# required for pvPortMalloc
 # tinyusb_device tinyusb_board (https://github.com/raspberrypi/pico-examples/blob/master/usb/device/dev_hid_composite/CMakeLists.txt)
-target_link_libraries(${MAIN} pico_stdlib pico_malloc pico_mem_ops hardware_adc pico_unique_id FreeRTOS-Kernel FreeRTOS-Kernel-Heap4 tinyusb_device tinyusb_board cmake_git_version_tracking)
+target_link_libraries(${MAIN} hardware_spi pico_stdlib pico_malloc pico_mem_ops hardware_adc pico_unique_id FreeRTOS-Kernel FreeRTOS-Kernel-Heap4 tinyusb_device tinyusb_board cmake_git_version_tracking)
 
 # stdio only on UART (UART0 by default, pins 1 and 2)
 pico_enable_stdio_usb(${MAIN} 0)

src/core/mcp3008/mcp3008.c

@@ -0,0 +1,81 @@
+#include "mcp3008.h"
+
+// gpio_set_function
+#include "pico/stdlib.h"
+
+spi_dual_inst mcp3008_init_hardware(spi_inst_t *spi, uint baudrate, spi_pinout_t *pinout)
+{
+ spi_dual_inst inst = {
+ .spi_hw = spi,
+ //.baudrate = baudrate,
+ .pinout = pinout};
+
+ // Init SPIx at specified baudrate
+ inst.baudrate = spi_init(inst.spi_hw, baudrate);
+
+ // Assign SPI functions to pins
+ gpio_set_function(inst.pinout->rx, GPIO_FUNC_SPI);
+ gpio_set_function(inst.pinout->sck, GPIO_FUNC_SPI);
+ gpio_set_function(inst.pinout->tx, GPIO_FUNC_SPI);
+ // gpio_set_function(5, GPIO_FUNC_SPI);
+
+ gpio_init(5);
+ gpio_set_dir(5, GPIO_OUT);
+ gpio_put(5, 1);
+
+ // Create an input buffer and initialise it to zero.
+ for (uint8_t i = 0; i < BUF_LEN; i++)
+ {
+ inst.input_buffer[i] = 0;
+ }
+
+ return inst;
+}
+
+// -- Internal function to handle sending data --
+#define OUTPUT_BUFFER_LEN 3
+uint16_t mcp3008_internal_do_adc(spi_dual_inst *inst, uint8_t channel, bool differential)
+{
+ // Create a buffer to sent to the device initialised to zero
+ uint8_t output_buffer[OUTPUT_BUFFER_LEN];
+ for (uint8_t i = 0; i < OUTPUT_BUFFER_LEN; i++)
+ {
+ output_buffer[i] = 0;
+ }
+
+ // Byte 1, leading zeros ending with a start bit
+ output_buffer[0] = 0x01;
+
+ // Byte 2
+ // Bit 1, differential signal sleection
+ // Bits 2-4 channel select
+ // Rest of buffer ignored
+ output_buffer[1] = ((differential ? 0 : 1) >> 7 | channel << 4);
+
+ // temp
+ uint8_t input_buffer[BUF_LEN];
+ for (uint8_t i = 0; i < BUF_LEN; i++)
+ {
+ input_buffer[i] = 0;
+ }
+
+ // Send the SPI command
+
+ gpio_put(5, 0);
+ spi_write_read_blocking(spi0, output_buffer, input_buffer, BUF_LEN);
+ gpio_put(5, 1);
+
+ printf("RECIEVED DATA");
+
+ uint16_t data = (((uint16_t)(input_buffer[1] & 0x03)) << 8) | input_buffer[2];
+
+ return data;
+
+ // Response
+ // 13 bits garbage
+ // 1 bit null (0)
+ // data, ordered bits 9 to 0
+ // mask 0x07 last 3 bits
+ // mask 0x03 last 2 bits
+ // return (((uint16_t)(input_buffer[1] & 0x03)) << 8) | input_buffer[2];
+}

src/core/mcp3008/mcp3008.h

@@ -0,0 +1,22 @@
+#ifndef MCP3008_H_
+#define MCP3008_H_
+
+#include "hardware/spi.h"
+
+#include "pinout.h"
+
+// TODO: can definitely get away with a smaller size
+#define BUF_LEN 3
+
+typedef struct
+{
+ spi_inst_t *spi_hw;
+ uint baudrate;
+ spi_pinout_t *pinout;
+ uint8_t input_buffer[BUF_LEN];
+} spi_dual_inst;
+
+spi_dual_inst mcp3008_init_hardware(spi_inst_t *spi, uint baudrate, spi_pinout_t *pinout);
+uint16_t mcp3008_internal_do_adc(spi_dual_inst *inst, uint8_t channel, bool differential);
+
+#endif /* MCP3008_H_ */

src/core/mcp3008/pinout.h

@@ -0,0 +1,7 @@
+typedef struct TU_ATTR_PACKED
+{
+ int rx;
+ int sck;
+ int tx;
+ int csn;
+} spi_pinout_t;