Introduction to PWM

Pulse width modulation (PWM) is a digital technique used for controlling an analog circuit.

A PWM controller can be implemented either using a microcontroller or an FPGA digital outputs.

The PWM is employed in a wide multiplicity of applications, ranging from measurement and communications to power control, conversion.

Read More

Connection of Serial ADC to FPGA

The ADC (Analog to Digital Converter) can be interfaced to FPGA/ASIC in a different way depending on the output interface. This post gives an overview of the different interfaces available in ADC interfacing. On modern ADC, when the sampling rate is below 10 Msample/sec the ADCs often implement a serial interface to provide sampled data to the user. The serial interface is a little bit complex w.r.t. a parallel interface but the use of serial protocol reduces the number of wires and allows interfacing the ADC to a microprocessor like Arduino or Raspberry Pi.

In the serial interface, the serial clock provided by the device connected to the ADC is also used as ADC sampling clock.

In this post, we will see an example of how to interface the TI ADC128S022 used in the Altera DE0-nano Board

Read More

Clock Design Overview

Often, inside our FPGA design, we have the necessity to generate a local clock from the system clock. With system clock, I mean the clock that is coming from an external board oscillator. Many modern FPGAs have the possibility to generate internal clocks, different from the external clocks, using internal PLL hard macro. So you can generate internal FPGA clock as multiple or sub-multiple of the external system clock.

 

Sometimes the PLL are used to modify the clock phase or to generate different clocks at the same frequency with different phase relationship. For instance, 3 clocks:

Read More