ECG data acquisition with Analog device frontend and Redbear nano BLE
Dependencies: BLE_API mbed nRF51822
Fork of BLENano_SimpleControls by
Reference Design
2 channel EKG with Redbear BLE reference and Analog Device amplifier to generate RAW EKG data fed into Medtrics MaaS service . Medtrics API can consumer raw input with given parameters of ADC sample frequency and scaling factor
Specification
- Application Processor: nRF51822/BLE , Analog frontend: AD8232 /
- Input Analog Voltage = 3.3V
- 10 bit ADC input range = (0-1023) or scaling factor= 3.22mV/unit (this is ADC resolution)
- ADC sample frequency (BLE pull rate) = 250Hz (4ms per sample)
Reference IOS and Android app will be online soon!
main.cpp
- Committer:
- RedBearLab
- Date:
- 2014-10-31
- Revision:
- 0:be2e4095513a
- Child:
- 1:81a97eb70d3d
File content as of revision 0:be2e4095513a:
#include "mbed.h" #include "BLEDevice.h" #include "Servo.h" #define BLE_UUID_TXRX_SERVICE 0x0000 /**< The UUID of the Nordic UART Service. */ #define BLE_UUID_TX_CHARACTERISTIC 0x0002 /**< The UUID of the TX Characteristic. */ #define BLE_UUIDS_RX_CHARACTERISTIC 0x0003 /**< The UUID of the RX Characteristic. */ #define TXRX_BUF_LEN 20 #define DIGITAL_OUT_PIN P0_9 //TXD #define DIGITAL_IN_PIN P0_10 //CTS #define PWM_PIN P0_11 //RXD #define SERVO_PIN P0_8 //RTS #define ANALOG_IN_PIN P0_4 //P04 BLEDevice ble; DigitalOut LED_SET(DIGITAL_OUT_PIN); DigitalIn BUTTON(DIGITAL_IN_PIN); PwmOut PWM(PWM_PIN); AnalogIn ANALOG(ANALOG_IN_PIN); Servo MYSERVO(SERVO_PIN); //Serial pc(USBTX, USBRX); static uint8_t analog_enabled = 0; static uint8_t old_state = 0; // The Nordic UART Service static const uint8_t uart_base_uuid[] = {0x71, 0x3D, 0, 0, 0x50, 0x3E, 0x4C, 0x75, 0xBA, 0x94, 0x31, 0x48, 0xF1, 0x8D, 0x94, 0x1E}; static const uint8_t uart_tx_uuid[] = {0x71, 0x3D, 0, 3, 0x50, 0x3E, 0x4C, 0x75, 0xBA, 0x94, 0x31, 0x48, 0xF1, 0x8D, 0x94, 0x1E}; static const uint8_t uart_rx_uuid[] = {0x71, 0x3D, 0, 2, 0x50, 0x3E, 0x4C, 0x75, 0xBA, 0x94, 0x31, 0x48, 0xF1, 0x8D, 0x94, 0x1E}; static const uint8_t uart_base_uuid_rev[] = {0x1E, 0x94, 0x8D, 0xF1, 0x48, 0x31, 0x94, 0xBA, 0x75, 0x4C, 0x3E, 0x50, 0, 0, 0x3D, 0x71}; uint8_t txPayload[TXRX_BUF_LEN] = {0,}; uint8_t rxPayload[TXRX_BUF_LEN] = {0,}; //static uint8_t rx_buf[TXRX_BUF_LEN]; //static uint8_t rx_len=0; GattCharacteristic txCharacteristic (uart_tx_uuid, txPayload, 1, TXRX_BUF_LEN, GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_WRITE | GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_WRITE_WITHOUT_RESPONSE); GattCharacteristic rxCharacteristic (uart_rx_uuid, rxPayload, 1, TXRX_BUF_LEN, GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_NOTIFY); GattCharacteristic *uartChars[] = {&txCharacteristic, &rxCharacteristic}; GattService uartService(uart_base_uuid, uartChars, sizeof(uartChars) / sizeof(GattCharacteristic *)); void disconnectionCallback(Gap::Handle_t handle, Gap::DisconnectionReason_t reason) { //pc.printf("Disconnected \r\n"); //pc.printf("Restart advertising \r\n"); ble.startAdvertising(); } void WrittenHandler(const GattCharacteristicWriteCBParams *Handler) { uint8_t buf[TXRX_BUF_LEN]; uint16_t bytesRead; if (Handler->charHandle == txCharacteristic.getValueAttribute().getHandle()) { ble.readCharacteristicValue(txCharacteristic.getValueAttribute().getHandle(), buf, &bytesRead); memset(txPayload, 0, TXRX_BUF_LEN); memcpy(txPayload, buf, TXRX_BUF_LEN); //for(index=0; index<bytesRead; index++) //pc.putc(buf[index]); if(buf[0] == 0x01) { if(buf[1] == 0x01) LED_SET = 1; else LED_SET = 0; } else if(buf[0] == 0xA0) { if(buf[1] == 0x01) analog_enabled = 1; else analog_enabled = 0; } else if(buf[0] == 0x02) { float value = (float)buf[1]/255; PWM = value; } else if(buf[0] == 0x03) { MYSERVO.write(buf[1]); } else if(buf[0] == 0x04) { analog_enabled = 0; PWM = 0; MYSERVO.write(0); LED_SET = 0; old_state = 0; } } } /* void uartCB(void) { while(pc.readable()) { rx_buf[rx_len++] = pc.getc(); if(rx_len>=20 || rx_buf[rx_len-1]=='\0' || rx_buf[rx_len-1]=='\n') { ble.updateCharacteristicValue(rxCharacteristic.getValueAttribute().getHandle(), rx_buf, rx_len); pc.printf("RecHandler \r\n"); pc.printf("Length: "); pc.putc(rx_len); pc.printf("\r\n"); rx_len = 0; break; } } } */ void m_status_check_handle(void) { uint8_t buf[3]; if (analog_enabled) // if analog reading enabled { // Read and send out float s = ANALOG; uint16_t value = s*1024; buf[0] = (0x0B); buf[1] = (value >> 8); buf[2] = (value); ble.updateCharacteristicValue(rxCharacteristic.getValueAttribute().getHandle(), buf, 3); } // If digital in changes, report the state if (BUTTON != old_state) { old_state = BUTTON; if (BUTTON == 1) { buf[0] = (0x0A); buf[1] = (0x01); buf[2] = (0x00); ble.updateCharacteristicValue(rxCharacteristic.getValueAttribute().getHandle(), buf, 3); } else { buf[0] = (0x0A); buf[1] = (0x00); buf[2] = (0x00); ble.updateCharacteristicValue(rxCharacteristic.getValueAttribute().getHandle(), buf, 3); } } } int main(void) { Ticker ticker; ticker.attach_us(m_status_check_handle, 200000); ble.init(); ble.onDisconnection(disconnectionCallback); ble.onDataWritten(WrittenHandler); //pc.baud(9600); //pc.printf("SimpleChat Init \r\n"); //pc.attach( uartCB , pc.RxIrq); // setup advertising ble.accumulateAdvertisingPayload(GapAdvertisingData::BREDR_NOT_SUPPORTED); ble.setAdvertisingType(GapAdvertisingParams::ADV_CONNECTABLE_UNDIRECTED); ble.accumulateAdvertisingPayload(GapAdvertisingData::SHORTENED_LOCAL_NAME, (const uint8_t *)"Biscuit", sizeof("Biscuit") - 1); ble.accumulateAdvertisingPayload(GapAdvertisingData::COMPLETE_LIST_128BIT_SERVICE_IDS, (const uint8_t *)uart_base_uuid_rev, sizeof(uart_base_uuid)); // 100ms; in multiples of 0.625ms. ble.setAdvertisingInterval(160); ble.addService(uartService); ble.startAdvertising(); //pc.printf("Advertising Start \r\n"); while(1) { ble.waitForEvent(); } }