Posts Tagged ‘A/D converter’

A/D converter 16Bit with LCD and PIC18F2550

The analog to digital converter (ADC) is a commonly required in most of the projects. Analog voltage measurement can be done using the ADC hardware built in together in a PIC. The picture below show a simple setup for measuring the voltage through the adjustment of the potentiometer. PIC used in this example come with a 10 bit ADC. In the picture the hex value shown is the ADC value acquired from the hardware. After a simple conversion the voltage can be obtain from this value.
The next step would be to configure the register on the PIC for the ADC to operate. ADCON0 sets the refrence voltage to Vdd and Vss and select AN0 as the input for the ADC. ADCON1 configure the PIN as analog input. Only PIN AN0 is selected as analog input in this example. ADCON2 sets the required time for acquisition. The value for TAD is choose based on the calculation in the datasheet (pic18f2455, page 298-299). ADC module is turn on for it to function. To display the floating point number conversion to string must be done. The function sprintf is use to format the output so that it can be showed on the LCD. The sprintf function provided by C18 can’t be used directly on a floating point number, so the number must 1st be breakup in to the digits left and right of the decimal point. The sprintf is used to join up the 2 parts and the floating point number is display out on the 2×16 lcd. A routine for reading of ADC value is created. The acquisition is started by setting the GO bit in ADCON0. Conversion is done when the done bits turn 0. The high and low byte of the ADC results are joined in to a 16 bit data and pass back from the function. A simple formula can be use to calculate the voltage from the ADC result. The result is multiply by the max value of reference voltage and divided by 1024. Doing this will obtain the voltage on the pin AN0. http://www.enmcu.com/guides/analogtodigitalconverteronpic18

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Here’s another daft yet interesting PIC12F675 idea I came up with. When I wanted to show someone how logic gates worked I could only find a NAND gate which wasn’t very handy for demonstrating AND’s OR’s, NOR’s and ExOR’s. I also wanted to have a play with the A/D converter on the 12F675 so I came up with the idea of a PIC that could function as a single 2-input logic element. The logic function is determined by an analogue voltage applied to the GPIO4 pin when the device is first reset, it isn’t sampled again after this so logic can’t be changed on the fly. The 3 MSBs of the A/D conversion give eight distinct voltage levels that map to specific logic functions.
Read Source: http://picprojects.org.uk/projects/logic/logicelement.htm

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Video speed 6-bit Flash A/D converter by CA3306

This circuit use the CA3306 a family of CMOS parallel (flash) analogue to digital converters designed for low power, high speed applications. The CA3306CE operates at sampling rates up to 10 million samples per second and the CA3306E up to 15 million samples per second permitting analogue signals with bandwidths up to 5MHz or 7.5MHz to be fully digitised to 6-bit accuracy. An overflow input allows two devices to be connected in parallel will permit conversion speed to be doubled.

Read more:http://www.next.gr/inside-circuits/
Video-speed-6-bit-Flash-A-D-converter-l5880.html