Based on GX1258 (alternative ADS1258) 12-lead ECG data acquisition box application program

At present, the use of compact size portable ECG machine is increasing, this paper focuses on the introduction of a good performance, easy to carry miniature 12-lead ECG signal digital acquisition module. The program uses precision, low-drift, low-power devices, the use of high-resolution analog-to-digital converter to achieve data acquisition, in the form of a streamlined circuit to achieve a 12-lead high sampling rate ECG signal acquisition, conversion and transmission, can improve the performance and reliability of the product.

The analog-to-digital converter in the scheme realizes digital ECG signal acquisition in the circuit, and its parameters and performance index will affect the complexity of the line and the sampling rate. The ECG signal is a weak bioelectric signal, the amplitude is generally 0.05~5mV, therefore, in order to realize the synchronous amplification and conversion of the 8-channel ECG signal, the analog-to-digital converter GX1258 (instead of ADS1258) is a very suitable choice.

ECG signal in the acquisition process is often mixed with a lot of noise interference signals, the greater impact of industrial frequency interference, polarization voltage interference, baseline drift and so on. The GXSC GX1258 is a 16-channel (multiplexed), low-noise, 24-bit analog-to-digital converter capable of stably acquiring ECG data in channel polling mode at channel scanning rates ranging from 1.8K to 23.7K.

The GX1258 operates from a unipolar +5V supply, allows a digital voltage range of 2.7V to 5.25V, and is available in a QFN-48 package.

Key features:

- Fixed channel or channel polling; Fixed channel data rate: 125kSPS

- Channel polling rate: 23.7kSPS/channel

- 16 single-ended or 8 differential inputs

- Unipolar (+5V) operation

- Low noise: 2.8μVRMS at 1.8kSPS

- 0.0003% integral nonlinearity

- DC stability (typical): 0.02 μV/°C offset drift, 0.4 ppm/°C gain drift

- Sensor break detection

- Conversion control pin

- Multiple outputs for external signal processing

- On-chip temperature, reference, detuning, gain and supply voltage readback

- 42mW power consumption; standby, sleep and shutdown modes

- 8 General Purpose Inputs and Outputs (GPIOs)

- 32.768kHz crystal oscillator or external clock