April | 2012 | Embedded Lab

Monthly Archives: April 2012

Testing active analog temperature sensors with a multimeter

Posted on April 26, 2012 by R-B 6 comments

There are quite a variety of active analog temperature sensor ICs that provide an output voltage proportional to the temperature. They usually don’t require any external calibration and signal conditioning, and as such their output can be directly fed to the input of an ADC for digital processing. A few examples of such sensors are LM34, LM35, TMP35/36/37, and MCP9701. If you are having any trouble using any of these sensors in your project, here is a quick way to test if your sensor is working or not.

Interfacing an external ADC chip to FPGA/CPLD

Posted on April 26, 2012 by R-B Leave a comment

Chris (from PyroElectro) has posted an article on interfacing an external ADC chip to FPGAs and CPLDs, which do not have A/D capabilities built-in. He illustrates the idea with an Altera EPM7128 and a MAX150 8-bit analog to digital converter IC. The test analog signal is derived using a potentiometer and the converted digital output is shown using an LED bargraph display. The interface between the CPLD and ADC has been implemented in VHDL.

Digital logic probe for troubleshooting TTL and CMOS circuits

Posted on April 19, 2012 by R-B 6 comments

A logic probe is considered as a stethoscope for engineers and technicians for debugging digital logic circuits that consists of logic gates, memories, registers, etc. A digital multimeter (DVM) can also be used for such analytical purposes but it gives you the numeric value of the voltage at a point instead of the logic state. Depending on whether the circuit is based on TTL or CMOS components, the voltage levels for logic 0 and 1 could be different for each family. DVM users, thus, have to calculate logic levels from the measured voltages, which consumes time and delays the troubleshooting procedure.

Lab 21: Servo motor control

Posted on April 7, 2012 by R-B 18 comments

A servo motor is a special geared DC motor equipped with an electronic circuit for controlling the direction of rotation, as well as the position, of the motor shaft. Because servo motors allows precise angular positioning of their output shaft, they are used extensively in robotics and radio-controlled cars, airplanes, and boats to control the motion of their various parts. In this lab session, we will first explore what a servo motor consists of and how it works and then illustrate how to interface it with a PIC microcontroller.

Using CMOS camera for sensing applications

Posted on April 6, 2012 by R-B 3 comments

Ibrahim Kamal from IKALOGIC informed me about his latest article on the use of CMOS camera for sensing applications posted on his website. It’s true that interfacing a CMOS camera with 8-bit microcontrollers has not been very common. There’s a stereotype that much faster and powerful microcontrollers are required to process the output of a CMOS camera, which may not always be true, as illustrated by Ibrahim Kamam. In fact, it all depends on the type of application you choose with a CMOS camera. The article discusses about the possibility of using a CMOS camera for sensing applications by reducing