How to use an inbuilt ADC in a CPLD?

[itsfebin]

machxo mini schematics

Hi,

I use a cpld (LCMXO2280 from Lattice Semi) to control an SMPS.

It has an in-built ADC circuit which I can use to sense the SMPS o/p voltage. I referred the datsheet but nothing much is mentioned about the same. How do you think can I make use of the in-built ADC in LCMXO2280? I see an A2D_IN pin. How can I get the ADC output?

If I program the device like,

input A2D_in; //analog i/p
reg [15:0] A2D_out; //to store o/p of inbuilt A2D
A2D_reg <= A2D_pin;

Can I have the ADC output in 16bit A2D_out register?

Please help.

Thanks and regards,
Febin

 

[lucbra]

analog to digital converter cpld

Hello Febin,

you must be mistaken. The MachXO doesn't have an A to D converter, nor has is an analog input!
I guess you are referring to the mixed signal product from Lattice.

Regards
Luc

 

[itsfebin]

machxo comparator

oopz. sorry about that. i mentioned it wrong. I am using the machXO mini development kit that has an in-buit A2D converter. LCMXO2280 is the heart if this mini development kit. And I would like know how to use the A2D converter on this kit. Like, how to access A2D's output?? how do I know where is this value stored and how many bits is A2D's digital output? I tracked the A2D input signal in the circuit provided in MACHXO'S datasheet and it ends up in a pin called D2A, which has to be an analog output. I could not get much info about this from the datasheet. Please help.

sorry once again for getting the question wrong.

warm regards,
Febin

 

[FvM]

cpld analog comparator

I am using the machXO mini development kit that has an in-buit A2D converter.

It hasn't. It's equipped with an analog comparator and a RC circuit as building block for a very basic single slope AD. Hopefully, you'll find a respective Lattice demonstration project, otherwise you can figure out the intended operation yourself. It's simple!

 

[lucbra]

As FvM wrote, it looks like you have to find out yourself. Maybe a local representative can help you further with advanced documentation.

But with the comparator stuffed on the board, don't expect too much!

I would recommend hooking up a serial (SPI or I²C) ADC/DAC. There are plenty to choose from...

Regards & good luck
Luc

PS have you bought this kit on the web or via a local disti/rep?