I’d really like to know how to “”convert”” an analog value to a digital one. In a word : I have an Arduino, a photoresistor, with a pull-down resistor. I want to know if the light is above or below a given threshold.
I know how to read the value with analogRead(photoResPin), and compare it to my threshold (in code), but I’d like to do that without software (only using digitalRead), handling that threshold in hardware.
Can you help me ?
I guess I can use a transistor, but don’t know how to “”precisely”” set the threshold (by changing the pull-down resistor value ?).
How can I convert an analog value to a digital one? – [Link]
Toumas decided to code his own capacitive touch sensors based on a closed source Atmel example where a single ADC pin is used for capacitive sensing. He reverse engineered it, and documented his results: [via]
I’ve been thinking of a project that needs a little bit more elegant user interface than your usual push buttons. Partly inspired by a video blog on Dave Jones’ EEVblog, I decided to look into capacitive touch buttons. The big issue unfortunately for me was that you usually need a separate chip for capacitive touch sensing. With some tricks, you can however use a normal microcontroller to do the job. Even using only a single pin and resistor.
Capacitive touch sensing with a single ADC pin – [Link]
The MAX11209 can do 18 bits at sample rates up to 120 Hz (true) or 480 Hz (4x oversampled). It has both external analog and internal digital scaling. There is +Vref and -Vref, as well as +Vin and -Vin, so you can set your own full-range scale and offset via analog voltages (many ADCs have only +Vref, so you can’t set your own analog offset above ground). Maximum Vin = 3.6 V. The data sheet claim that CS/ can be tied low is apparently false (must be brought high after each SPI transaction).
The 11209 is part of a family, some other variants do 24 bits (although there I think some bits will be just noise). With the 11209 I can so far confirm that the input noise is less than 2 uV at a 15 Hz rate. Datasheet claims 0.57 uV RMS at 10 Hz.
Using the MAX11209 18bit ADC – [Link]
Free online data conversion handbook from Analog Devices. It covers everything you’ll need to get started with analog-to-digital and digital-to-analog converters. It’s not just reference designs, but also theory on how various architectures function – [via]
The Data Conversion Handbook, edited by Walt Kester (Newnes, 2005), is written for design engineers who routinely use data converters and related circuitry. Comprising Data Converter History, Fundamentals of Sampled Data Systems, Data Converter Architectures, Data Converter Process Technology, Testing Data Converters, Interfacing to Data Converters, Data Converter Support Circuits, Data Converter Applications, and Hardware Design Techniques, it may be the ultimate expression of product “augmentation” as it relates to data converters. The last chapter discusses practical issues, including common pitfalls and solutions related to the non-ideal properties of passive components.
App note: Analog and digital conversion handbook – [Link]
Here is an app note from Microchip explaining how to interpret various analog to digital converter specifications. This article covers how attributes of ADCs are calculated and how they apply to it’s performance and precision – [via]
The purpose of this application note is to describe the specifications used to quantify the performance of A/D
converters and give the reader a better understanding of the significance of those specifications in an application.
App note: Understanding ADC specifications and attributes – [Link]
This is a simple application of internal 10-bit ADC (analog to digital converter) of PIC16F676 microcontroller.you can use this circuit to measure up to 30 v dc. the possible applications are on bench top power supply or as a panel meter in various system.
MICROCHIP’S PIC16F676 is the heart and brain of this circuit .the internal adc of the mcu with a resistor network voltage divider is used to measure the input voltage . then 3 digest of comm anode 7 segment display is used to display final converted voltage. as you can see in the schematic the displays are multiplexed with each other . means we switch on one display and put the corresponding digit on this while other two displays are off this cycle go for each of the display.
Panel Voltmeter Using PIC16F676 – [Link]
This is a simple application of internal 10-bit ADC (analog to digital converter) of MSP430G2231 microcontroller.you can use this circuit to measure up to 30 Vdc. the possible applications are on bench top power supply or as a panel meter in various system.
TEXAS INSTRUMENTS MSP430G2231 is the heart and brain of this circuit .the internal adc of the mcu with a resistor network voltage divider is used to measure the input voltage . then 3 digest of comm anode 7 segment display is used to display final converted voltage. as you can see in the schematic the displays are multiplexed with each other . means we switch on one display and put the corresponding digit on this while other two displays are off this cycle go for each of the display.
MSP430 based 30V voltmeter – [Link]
This is a simple rf spectrum analyzer project based on TI Launchpad. i have been working on other rf transceiver projects and in need of a simple rf spectrum analyzer to help me visualize what’s happening.
This is a linux project, i had given attention with my best knowledge to make provisions so that it can be built under windows. however i do not have the time and resources to try out everything under windows.
I did successfully built and run the project under windows 7 w/ TI CCS IDE, for host visualization script, it also works under windows but required you to install some unixish packages (cygwin and more)
I need something simple to show the pattern of frequency hopping. i do not need very accurate display of rf power. the Launchpad came in handy as it is inexpensive and contains fast ADC functions. the included usb to uart is a plus as i can communicate data between the MCU application w/ a PC side application for visualization. there are around a dozen or so commands that you can issue via SPI to control the RFM12B, as well as sending and receiving data.
RFM12B Spectrum Analyzer – [Link]
element14, Microchip and Matrix introduce the new PIC18 Flowcode Developers Kit. Lowers the barrier to electronics design with easy to use Graphical Programming
30 January 2012 – London, element14, the first collaborative global electronics community from Premier Farnell plc (LSE:pfl), has teamed up with Microchip and Matrix to introduce the new PIC18 Flowcode Developers Kit. This innovative development and demonstration kit is designed to offer a hands-on, easy approach to electronics design using Flowcode, one of the world’s most advanced graphical programming languages for microcontrollers.
The development platform is based on a Microchip PIC18F26J50 low power, 8-bit PIC18F26J50 microcontroller, and is integrated with temperature sensor, capacitor touch sensor and potentiometer to help developers verify programs designed using Flowcode.
“The new PIC18 Flowcode Developers Kit is an innovative, fully featured yet low cost solution designed to help developers realize their designs in working hardware,” says Mike Powell, Technology Development Manager, Premier Farnell. “Optimized for Flowcode development, the board has several expansion options, it can be used as a black box and is mounted with a PIC 18 device that is low power, but high performance.
The competitive advantage of Flowcode is that it allows those with little-to-no programming experience to create electronic systems in minutes. Flowcode supports code generation for the PIC® (PIC12, PIC16, and PIC18 series ), PIC24 and dsPIC® series of microcontrollers. The professional edition includes drivers for a range of sub-systems including LCDs, keypads, seven-segment displays, ADC and PWM, as well as communication protocols including I2C, SPI, RS-232RS-232, Zigbee and TCP/IP, among others.
Flowcode is compatible with Microchip’s PICkit programmer as well as third party programmers. It is also compatible with the HI-TECH C compiler. A ‘Lite’ version of Flowcode 4 is included in the kit.
For more information visit element14.
This circuit is a digital sound level meter with a LCD screen, capable of displaying 80 characters (4 rows with 20 characters on each). You can build this LCD display. It also provides more debugging information, such as the minimum and maximum analog-to-digital samples that were measured during each period. [via]
Digital Sound Level Meter – [Link]