Chris The Carpenter has put together possibly the most complete robot module for the Propeller Platform. Called the 444AVXB, he writes… [via]
Let’s start with the name, 444-AVXB stands for:
4 Amps (2 amps x 2 motors) via a L298 motor driver
4 ADC’s (Analog inputs) via a MCP3204 chip
4 Servos with connections to power and with current-limiting resistors on the signal wires
Video-out via a standard RCA jack
Connections for an X-bee
Connections for a BlueSmirf Bluetooth unit
he 444-AVXB was designed with the robot hobbyist in mind. Connections are available for just about every “standard” thing you would find on a small to medium-sized robot. A hefty motor driver handles decent-sized motors with nice screw terminals for both power and motor connections. (4) 3-pin connections are provided for servos which can be powered by either external power or on-board power. An ADC chip allows for 4 analog inputs to be read, great for analog sensors, pots, LDR’s etc.
Video-out takes advantage of the awesome video capability of the prop and can be connected to any TV with a “video-in” and/or many of the cheapie 7” LCD screens (found on Ebay). Audio is just that, audio out with the circuit being the same as can be found on many other propeller products. Pin 15 has been brought forward as well for a Ping))) sonar unit. Finally, there is room and connections for EITHER an X-bee or Bluetooth module. All unused pins are accessible via female headers.
A Robot Module with Everything – [Link]
This little board demonstrates the capabilities of the MMA2260 +/- 1.5g X-Axis Micromachined Accelerometer. As you tip it back and forth, LEDs light up to show the magnitude and direction of the G force.
The MMA2260 is the fat SOIC 16 in the upper left, isolated so it could be cut off of the board and used as a breakout, keeping only a pin header and the recommended decoupling and output RC filter.
The microcontroller is a PIC16F628, which is entirely unsuited to this application, having no ADC. I failed to notice that, being quick to note “AN0″ on PORTA and slow to note that it was for a comparator, not an ADC. However, there is a builtin programmable voltage reference which was sufficiently accurate for lighting up 8 LEDs. I’m trying to get away from PICs, as AVRs have spoiled me with their GCC support, many registers and sane memory organization. Even on this project, which is only about 30 lines of C, most of the work was fighting SDCC bugs (failure to banksel, in this case). I’ve discovered a perverse pleasure in soldering down ICs to counteract my packrat nature. It did force me to put an ICSP header on, however.
MMA2260 Accelerometer Demo – [Link]
The PIC16F690 microcontroller is one of Microchip midrange 8-bit microcontroller that has a build in 10-bit resolution of Analog to Digital Converter (ADC) peripheral. The ADC is one of the important features that enable us to digitize our analog world. Usually we use the electronic sensor to convert the analog value to the voltage level value. Some of the basic sensor such as LDR (Light Dependent Resistor) is used for measuring the light intensity or NTC (Negative Temperature Coefficient) a special resistor for measuring the temperature.
PIC Analog to Digital Converter C Programming – [Link]
Sometimes we need our microcontroller to interact with more human readable information. It will be better for us if we could make it display the words not just blinking the LED. Today most modern gadget such as mobile phone and PDA, use LCD (Liquid Crystal Display) for interacting with us. In this project we will learn how to use the 2×16 LCD for displaying the room’s temperature.
Actually driving the LCD hardware directly is a complex task, but luckily we don’t have to do that; in the market they have already put it together in one package the LCD display hardware and the microcontroller that control it, so our task will be easier now as we only talk to the build in microcontroller inside. The most famous on the market is the 2×16 LCD with LED backlight using Hitachi HD44780U or the equivalent microcontroller, this 80 pins microcontroller is a special dot matrix LCD driver controller with low power consumption and able to use 4-bit data or 8-bit data interface; my suggestion is to have this HD44780U datasheet near you as we walk through this project.
AVR LCD Thermometer Using ADC and PWM Project – [Link]
It’s interesting to explore what we can do with this tiny 8 pins; 8-bit microcontroller. The ATtiny13 is the smallest and cheapest Atmel AVR 8-bit microcontroller families but yet, it’s loaded with sophisticated peripherals such as two 8-bit PWM channels and 4 channels 10-bit ADC. Although the memory is quite small; 1 K flash, 64 SRAM and 64 EEPROM but this more the adequate for most PWM and ADC application, if you need more memory, bellow is the list of other Atmel AVR 8 pins microcontrollers which have compatible pins with ATtiny13 microcontroller.
Controlling DC motor with AVR ATtiny13 PWM and ADC Project – [Link]
If you’re interested in how delta-sigma modulators and ADCs work, you should check out this excellent introduction by Uwe Beis: [via]
When looking for an introduction to delta sigma conversion I found that most explanations were from a very theoretical point of view. It took me a while to understand how Delta Sigma converters really work. So I decided to write this introduction for people who prefer circuit diagrams to reading abstract equations.
To understand what I’m talking about you should at least be familiar with:
– Standard analogue techniques (op-amps, comparators etc.)
– Standard digital techniques (latches, binary codes etc.)
– Standard ADCs and DACs (resolution, speed)
– What a low pass filter is (at least an analogue one)
– The sampling theorem (sample frequency > 2 x input bandwidth, alias effects)
Delta sigma converters are different from other converters. Note that I do not make a difference between analogue-to-digital (ADC) and digital-to-analogue converters (DAC). Both are very similar and what is realized in one of them using analogue signal processing circuitry is implemented in the other one using digital signal processing and vice versa. I will explain the delta sigma technique with the analogue-to-analogue delta sigma converter as the first object.
An Introduction to Delta-Sigma Converters – [Link]
Wichit Sirichote writes:
This is my student assignment for the class “Designing Microprocessor Based Instrumentation”. The board demonstrates the use of 12-bit ADC, writing c program with digital filtering and interface the LED display. The reading provides 0.1C sensitivity. The optional input of the ADC is available for exercise with other input signals or sensors.
Thermistor Thermometer – [Link]
Another article that might help with bench power supply designs:
Current-Sense Amplifiers with Digital Output and 60V Common-Mode Range
- Offers easy interface with microcontrollers (supports 1.8V logic) by using digital outputs
- Delivers wide 60V common-mode range for robustness under fault conditions
- Includes internal op amp/comparator that allows flexibility in system design: the internal amplifier can be used to limit the inrush current or to create a current-source in a closed loop system; the comparator can be used to monitor fault events for fast response
High-side, current-sense amplifiers with 12-bit ADC and op amp/comparator – [Link]
One of the important features in today’s modern microcontroller is the capability of converting the analog signal to the digital signal. This feature allows us to process the analog world easily such as temperature, humidity, light intensity, distance, etc; which usually captured by electronics sensor and represent it on the change of voltage level.
Analog to Digital Converter AVR C Programming – [Link]
Here is my home-made kit of ATmega32 microcontroller interfacing. The ATmega32 controller is rich with features like onboard 32kB in-System programmable flash, 1 KB EEPROM, 2KB SRAM, 10bit ADC (8 channel), SPI bus inteface, TWI (compatible with I2C bus) interface, an USART, analog comparator, etc. That’s why I’ve selected it to load my kit with all those features.
Make-Yourself ATmega32 Starter’s Kit with LCD, I2C, SPI, RTC, ADC interfaces – [Link]