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!
Diff: main.cpp
- Revision:
- 0:be2e4095513a
- Child:
- 1:81a97eb70d3d
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/main.cpp Fri Oct 31 09:47:34 2014 +0000 @@ -0,0 +1,232 @@ + +#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(); + } +} + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +