ok then you will be using two ADC0808 (I dont know if an ADC for 16 analog inputs exists or not?) The third IC will be a microcontroller. The 1st ADC's output goes to the first port of the microcontroller and similarly the 2nd ADC's output to the 2nd port. Next the microcontroller will be controlling the select lines of the two ADCs. There are three select line for each ADC.
If you use 8051 controller probably you can get a ready to use interface for the serial port.
Ok now coming to the programming algo of the microcontroller
START:
1- Send 000 to the select lines of 1st adc and read the analog value on the portA and send it to the serial interface.
2- Send 001 to the select lines of 1st adc and read the analog value on the portA and send it to the serial interface.
3- Send 010 to the select lines of 1st adc and read the analog value on the portA and send it to the serial interface.
4-Send 011 to the.......
5-Send 100 to the.......
6-Send 101 to the.......
7-Send 110 to the.......
8-Send 111 to the.......
9- Send 000 to the select lines of 2nd adc and read the analog value on the portB and send it to the serial interface.
10- Send 001 to the select lines of 2nd adc and read the analog value on the portB and send it to the serial interface.
11- Send 010 to the select lines of 2nd adc and read the analog value on the portB and send it to the serial interface.
12-Send 011 to the.......
13Send 100 to the.......
14-Send 101 to the.......
15-Send 110 to the.......
16-Send 111 to the.......
GO TO START