Converting signed 8-bit sample codes to volts Sample Clauses

Converting signed 8-bit sample codes to volts. A signed code of 0 represents ~0V input voltage, 127 (0x7F) represents a positive full- scale input voltage, and –128 (0x80) represents a negative full-scale input voltage. The following table illustrates how signed 8-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 -127 0x81 -100% -100 mV -1 V -64 0xC0 -50% -50 mV -.5 V 0 0x00 0% 0 V 0V 64 0x40 +50% 50 mV +.5 V 127 0x7F +100% +100 mV +1 V The following code fragment shows how to convert a 1-byte sample value containing a signed 8-bit sample code to in volts. double SampleToVoltsS8(U8 sampleValue, double inputRange_volts) { // AlazarTech digitizers are calibrated as follows int bitsPerSample = 8; double codeZero = (1 << (bitsPerSample - 1)) - 0.5; double codeRange = (1 << (bitsPerSample - 1)) - 0.5; // Convert signed code to unsigned U8 sampleCode = sampleValue + 0x80; // Convert sample code to volts double sampleVolts = inputRange_volts * ((double) (sampleCode - codeZero) / codeRange); return sampleVolts; }