Converting signed 12-bit sample codes to volts Sample Clauses

Converting signed 12-bit sample codes to volts. A signed code of 0 represents ~0V input voltage, 2047 (0x7FF) represents a positive full- scale input voltage, and -2048 (0x800) represents a negative full-scale input voltage. The following table illustrates how signed 12-bit sample codes map to values in volts according to the full-scale input range of the input channel. Sample code in decimal Sample code in hex Sample value as a percentage of full- scale input range Sample value in volts if full-scale input range is ±100 mV Sample value in volts if full- scale input range is ±1 V -2047 0x801 -100% -100 mV -1 V -1024 0xC00 -50% -50 mV -.5 V 0 0x000 0% 0 V 0V 1024 0x400 +50% 50 mV +.5 V 2047 0x7FF +100% +100 mV +1 V The following code fragment shows how to convert a 2-byte sample word containing a signed 12-bit sample code to in volts. double SampleToVoltsS12(U16 sampleValue, double inputRange_volts) { // Right-shift 16-bit sample value by 4 to get 12-bit sample code int bitShift = 4; U16 sampleCode = sampleValue >> bitShift; // Convert signed code to unsigned sampleCode = (sampleCode + 0x800) & 0x7FF; // AlazarTech digitizers are calibrated as follows int bitsPerSample = 12; double codeZero = (1 << (bitsPerSample - 1)) - 0.5; double codeRange = (1 << (bitsPerSample - 1)) - 0.5; // Convert sample code to volts double sampleVolts = inputRange_volts * ((double) (sampleCode - codeZero) / codeRange); return sampleVolts; }