1-Channel DC Current Monitor I2C Mini Module

prowe · September 21, 2018, 7:02pm

I am using the 1-Channel DC Current Monitor I2C Mini Module, The code below shows my algorithm to convert the data returned to the actual voltage returned by the A2D chip on the board. Is this code correct?

int msb, lsb;

short int lnbResult = wiringPiI2CReadReg16 (( lnbNumber == 1 ? lnb1 : ( lnbNumber == 2 ? lnb2 : lnb3 ) ), 0x00);

if ( lnbResult > 0 )
{
msb = lnbResult & 0xFF;
lsb = lnbResult >> 8;

 int rawADC = msb * 256 + lsb;
 rawADC = rawADC &amp; 0x0FFF;
 double volt = rawADC * 5.0 / 4096.0;

return volt;

}

Thanks

Bhaskar · September 21, 2018, 7:59pm

the adc output is 12bit so i beleive
msb = lnbResult & 0xFF;
lsb = lnbResult >>8;

should be this
msb = lnbResult & 0x0F;
lsb = lnbResult;

this lib might be helpful as well

github.com

ncdcommunity/Raspberry_Pi_ADC121C_ACS714_1Channel_Dc_Current_Monitoring_Sensor_Python_library/blob/master/ADC121C_ACS714.py

# Distributed with a free-will license.
# Use it any way you want, profit or free, provided it fits in the licenses of its associated works.
# ADC121C_ACS714
# This code is designed to work with the ADC121C_I2CS_ACS714 I2C Mini Module available from ControlEverything.com.
# https://www.controleverything.com/content/Hall-Effect?sku=ADC121C_I2CS_ACS714#tabs-0-product_tabset-2
# NT

import smbus
import time

# Get I2C bus
bus = smbus.SMBus(1)

# I2C address of the device
ADC121C_ACS714_DEFAULT_ADDRESS			= 0x50

class ADC121C_ACS714():
	def read_data(self):
		"""Read data back from the device, 2 bytes
		raw_adc MSB, raw_adc LSB"""

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Thanks