{"id":221,"date":"2022-03-14T15:22:22","date_gmt":"2022-03-14T15:22:22","guid":{"rendered":"https:\/\/www.bleuio.com\/blog\/?p=221"},"modified":"2022-07-01T10:25:34","modified_gmt":"2022-07-01T10:25:34","slug":"show-bluetooth-le-sensor-readings-on-lcd-screen-connected-to-stm32","status":"publish","type":"post","link":"https:\/\/www.bleuio.com\/blog\/show-bluetooth-le-sensor-readings-on-lcd-screen-connected-to-stm32\/","title":{"rendered":"Show Bluetooth LE Sensor readings on LCD screen connected to STM32"},"content":{"rendered":"\n

The aim of this Bluetooth LE project<\/a> is to read air quality sensor data and show it on an LCD display which is connected to STM32 board. A web browser will read the sensor data and pass it to STM32 board using BleuIO.<\/p>\n\n\n\n

1. Introduction<\/h2>\n\n\n\n

The project is based on STM32 Nucleo-144<\/strong> which controls LCD display<\/strong> using BleuIO.<\/p>\n\n\n\n

For this project, we will need two BleuIO USB dongles<\/a>, one connected to the Nucleo board and the other to a computer running the web script and a HibouAir \u2013 Air quality monitoring device<\/a> .
When the BleuIO Dongle is connected to the Nucleo boards USB port the STM32 will recognize it and directly start advertising. This allows the Dongle on the computer port connect with the web script.<\/p>\n\n\n\n

With the web script on the computer, we can scan and get air quality sensor data from HibouAir. Then we send these data to LCD screen connected to STM32 using Bluetooth.<\/p>\n\n\n\n

We have used a STM32 Nucleo-144 development board with STM32H743ZI MCU (STM32H743ZI micro mbed-Enabled Development Nucleo-144 series ARM\u00ae Cortex\u00ae-M7 MCU 32-Bit Embedded Evaluation Board) for this example. This development board has a USB host where we connect the BleuIO dongle.<\/p>\n\n\n\n

If you want to use another setup you will have to make sure it support USB Host and beware that the GPIO setup might be different and may need to be reconfigured in the .ioc file.<\/p>\n\n\n\n

About the Code<\/h2>\n\n\n\n

The project source code is available at Github.<\/p>\n\n\n\n

https:\/\/github.com\/smart-sensor-devices-ab\/stm32_ble_sensor_lcd.git<\/a><\/p>\n\n\n\n

Either clone the project, or download it as a zip file and unzip it, into your STM32CubeIDE workspace.<\/p>\n\n\n\n

If you download the project as a zip file you will need to rename the project folder from \u2018stm32_bleuio_lcd-master\u2019 to \u2018stm32_bleuio_lcd\u2019<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Connect the SDA to PF0 on the Nucleo board and SCL to PF1.<\/p>\n\n\n\n

Then setup I2C2 in the STM32Cube ioc file as follows. (Make sure to change the I2C speed frequency to 50 KHz as per LCD display requirements.)<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n
\"\"<\/figure>\n\n\n\n
\"\"<\/figure>\n\n\n\n

In the USBH_CDC_ReceiveCallback function in USB_HOST\\usb_host.c we copy the CDC_RX_Buffer into a external variable called dongle_response that is accessable from the main.c file.<\/p>\n\n\n\n

void USBH_CDC_ReceiveCallback(USBH_HandleTypeDef *phost)\n{\n  \tif(phost == &hUsbHostFS)\n  \t{\n  \t\t\/\/ Handles the data recived from the USB CDC host, here just printing it out to UART\n  \t\trx_size = USBH_CDC_GetLastReceivedDataSize(phost);\n\t\tHAL_UART_Transmit(&huart3, CDC_RX_Buffer, rx_size, HAL_MAX_DELAY);\n\n\t\t\/\/ Copy buffer to external dongle_response buffer\n\t\tstrcpy((char *)dongle_response, (char *)CDC_RX_Buffer);\n\n\t\t\/\/ Reset buffer and restart the callback function to receive more data\n\t\tmemset(CDC_RX_Buffer,0,RX_BUFF_SIZE);\n\t\tUSBH_CDC_Receive(phost, CDC_RX_Buffer, RX_BUFF_SIZE);\n  \t}\n\n  \treturn;\n}\n<\/code><\/pre>\n\n\n\n
In main.c we create a simple intepreter so we can react to the data we are recieving from the dongle.<\/p>\n\n\n\n
void dongle_interpreter(uint8_t * input)\n{\n\n\tif(strlen((char *)input) != 0)\n\t{\n\t\tif(strstr((char *)input, \"\\r\\nADVERTISING...\") != NULL)\n\t\t{\n\t\t\tisAdvertising = true;\n\t\t}\n\t\tif(strstr((char *)input, \"\\r\\nADVERTISING STOPPED\") != NULL)\n\t\t{\n\t\t\tisAdvertising = false;\n\t\t}\n\t\tif(strstr((char *)input, \"\\r\\nCONNECTED\") != NULL)\n\t\t{\n\t\t\tisConnected = true;\n\t\t\tHAL_GPIO_WritePin(GPIOE, GPIO_PIN_1, GPIO_PIN_SET);\n\t\t}\n\t\tif(strstr((char *)input, \"\\r\\nDISCONNECTED\") != NULL)\n\t\t{\n\t\t\tisConnected = false;\n\t\t\tHAL_GPIO_WritePin(GPIOE, GPIO_PIN_1, GPIO_PIN_RESET);\n\t\t}\n\n\n\t\tif(strstr((char *)input, \"L=0\") != NULL)\n\t\t{\n\n\t\t\tisLightBulbOn = false;\n\t\t\t\/\/HAL_GPIO_WritePin(Lightbulb_GPIO_Port, Lightbulb_Pin, GPIO_PIN_RESET);\n\t\t\tlcd_clear();\n\n\t\t\twriteToDongle((uint8_t*)DONGLE_SEND_LIGHT_OFF);\n\n\t\t\tuart_buf_len = sprintf(uart_tx_buf, \"\\r\\nClear screen\\r\\n\");\n\t\t\tHAL_UART_Transmit(&huart3, (uint8_t *)uart_tx_buf, uart_buf_len, HAL_MAX_DELAY);\n\t\t}\n\n\t\tif(strstr((char *)input, \"L=1\") != NULL)\n\t\t{\n\t\t\t\tisLightBulbOn = true;\n\t\t\t\twriteToDongle((uint8_t*)DONGLE_SEND_LIGHT_ON);\n\n\n\t\t\t\tlcd_clear();\n\n\t\t\t\tlcd_write(input);\n\n\t\t}\n\n\t}\n\tmemset(&dongle_response, 0, RSP_SIZE);\n}<\/code><\/pre>\n\n\n\n
We put the intepreter function inside the main loop.<\/p>\n\n\n\n
\/* Infinite loop *\/\n  \/* USER CODE BEGIN WHILE *\/\n  while (1)\n  {\n    \/* USER CODE END WHILE *\/\n    MX_USB_HOST_Process();\n\n    \/* USER CODE BEGIN 3 *\/\n    \/\/ Simple handler for uart input\n    handleUartInput(uartStatus);\n\n    \/\/ Inteprets the dongle data\n    dongle_interpreter(dongle_response);\n\n\t\/\/ Starts advertising as soon as the Dongle is ready.\n\tif(!isAdvertising && !isConnected && isBleuIOReady)\n\t{\n\t\tHAL_Delay(200);\n\t\twriteToDongle((uint8_t*)DONGLE_CMD_AT_ADVSTART);\n\t\tisAdvertising = true;\n\t}\n  }\n  \/* USER CODE END 3 *\/<\/code><\/pre>\n\n\n\n
Using the example project<\/h2>\n\n\n\n
What we will need<\/h3>\n\n\n\n