8 channel 12 bit adc

[schlen]

 Hello friends,
i am new on this forum, it is good for me to improve my english and electronic. I have a thesis. My teacher want me to make adc with pc controlled via usb. I think that i can use serial to usb converter. But i doN't know how to use spi mode on 16f877

[Kabron]

First, PIC has 8x 10bit ADC not 12. But there is a way to get more resolution. It is a common approach allmost for any ADC. If you try a search of a topic like:
"Improving ADC Resolution By Oversampling", you'll find a lot of info from the various manufacturers. The technique is very sample and stable for resolutions up to 14 bits.
I widelly use it in my designs.
Second, you need no use spi. This PIC has full function UART which could be directly connected to say FT232R chip. 

[pickit2]

Why use a converter when some 18Fxxxx devices have USB built in see 18F2550 & 18F4550.
Search the Microchip website for the “PICDEM FS USB DEMO BOARD� that uses 18F4550.
You can download a schematic and software for the board.
The demo software will let you program the chip with your HEX file.

[alsabbag]

If you can get a USB supporting PIC device then go for it. I have faced problems running through the USB - Serial converter (Tried two types without much success). I have a Picall kit which runs fine with standard RS232 but fails with the converter.

[mculove]

Hi! Friend:

You could use 18F4553, 18F4458, 18F2553, 18F2458.
http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1335&dDocName=en530214

[schlen]

firs thank u for ur replies, but i have a problem here, i can't find 18xxx series pics here. I am in Ankara/Turkiye. If i use pic that has usb, does the pc need driver file to work with it? has it been prepared by manufacturer? Must i write driver files?

and i have max188 and max186. tehey are adc ICs. so i can use 16f877,can't i?

[bbarney]

First I would really try hard to find a 18f series pic it will make life simpiler for you in the long run and here's a really good example for you with most question's already answered

http://www.picbasic.co.uk/forum/showthread.php?t=5418

[Roshan]

Hi All !

PIC18f4550 has built in usb & you can use it as cdc device.

When you plug it in usb port it will create one virtual com port on your pc. Now same software which you have written for com port will work for usb device.

Roshan