Tag Archives: ADC

Read multiple switches using ADC




by Les Hughson @ edn.com:

The ATMega168 is a great general purpose 8-bit AVR microcontroller from Atmel. It has 23 GPIO pins, but sometimes (as I have found) you can run out of I/O pins as your design grows. This happened to me recently when, of the 23 GPIO pins available, 2 were taken up by an external ceramic resonator, 1 for the reset line, 3 for serial coms, 14 for the LCD, and 3 for RGB LED control. This used all 23 GPIO pins, with none left for the four buttons I needed. What to do? This Design Idea has the solution.

A close look at the ATMega168 data sheet revealed that the I/O pins available on the 28-pin DIP package and on the 32-pin TQFP package are not all the same. On the TQFP package, there are an additional pair of VCC & GND pins and an additional two ADC input pins on top of the advertised 23 GPIOs. So if I could read my 4 buttons with these extra ADC inputs, all would be OK and the design would be saved.

Read multiple switches using ADC – [Link]

Basic Temperature Control for Refrigerators



This design is a basic temperature control for refrigerators that has an electromechanical circuit. It specifically uses MC9RS08KA4CWJR microcontroller which has an 8-bit RS08 central processing unit, 254 bytes RAM, 8Kbytes flash, two 8-bit modulo timers, 2-channel 16-bit Timer/PWM, inter-integrated circuit BUS module, keyboard interrupt, and analog comparator. This project effectively controls temperature of any device using resistors and capacitors.

The refrigerator temperature control is a basic RC network connected to an I/O pin. A variable resistor (potentiometer) is used to modify the time the capacitor takes to reach VIH and adjusting its resistance varies that time. A basic voltage divider with one resistor and one thermistor is used to implement the temperature sensor. The thermistor resistance depends on the temperature. For each temperature, we have a different voltage in the divider. This value is effectively measured with the Analog-to-Digital Converter (ADC) implemented by software that uses one resistor, one capacitor, and the analog comparator. In addition, VDD and VSS are the primary power supply pins for the MCU. This voltage source supplies power to all I/O buffer circuitry and to an internal voltage regulator. The internal voltage regulator provides a regulated lower-voltage source to the CPU and other MCU internal circuitry.

This temperature control will not only be applicable to refrigerators but also to electronic devices that need temperature monitoring. It is a low cost device that may be integrated to appliances, medical and industrial equipment.

Basic Temperature Control for Refrigerators – [Link]

SoC Remote Control Platform for IEEE 802.15.4 Standard

The IEEE 802.15.4 standard is the fourth task group of the IEEE 802.15 working group, which defines Wireless Personal Area Network (WPAN) standards. The IEEE 802.15.4 market has the following advantages; low power consumption, low cost, low offered message throughput, supports large network orders up to 65k nodes, low to no QoS guarantees, and flexible protocol design suitable for many applications. The purpose for this standard is to empower simple devices with a reliable, robust wireless technology that could last for years on standard primary batteries. It is designed to allow developers to effectively use and benefit from radios based upon the standard.

This reference design is a low cost System-on-Chip (SoC) solution for the IEEE 802.15.4 standard that incorporates a complete, low power, 2.4GHz radio frequency transceiver with TX/RX switch, an 8-bit HCS08 CPU, and a functional set of MCU peripherals into a 48-pin LGA package. This product targets wireless RF remote control and other cost-sensitive applications ranging from home TV and entertainment systems to medical and supports all ZigBee node types. The Freescale’s MC13237 is a highly integrated solution, with very low power consumption. The MC13237 contains an RF transceiver that is an 802.15.4 standard 2006 compliant radio that operates in the 2.4GHz ISM frequency band. The transceiver includes a low noise amplifier, 1mW nominal output Power Amplifier (PA), internal Voltage Controlled Oscillator (VCO), integrated transmit/receive switch, on-board power supply regulation, 12-bit ADC and full spread-spectrum encoding and decoding.

This design is not only limited for remote controls. It can also be used as the basis for wireless devices and other sensor-controlled application that used IEEE 802.15.4 standard. The IEEE 802.15.4 radios have the potential to be the cost-effective communications backbone for simple sensory mesh networks that can effectively carry data with relatively low latency, high accuracy, and the ability to survive for a very long time on small primary batteries.

SoC Remote Control Platform for IEEE 802.15.4 Standard – [Link]

Playing with analog-to-digital converter on Arduino Due




Piotr wrote a post on his blog about using some of advanced capabilities of ADC in Arduino Due:

Today I’m going to present some of more advanced capabilities of ADC built in ATSAM3X8E – the heart of Arduino Due.
I like the Arduino platform. It makes using complex microcontrollers much simpler and faster. Lets take for example the analog-to-digital converter. To configure it even on Atmega328 (Arduino Uno/Duemilanove) you must understand and set correct values in 4 registers. And it can be much more in complex device, like 14 in ATSAM3X8E (Arduino Due)!

Playing with analog-to-digital converter on Arduino Due – [Link]

A data-acquisition system on a chip


by Martin Rowe @ edn.com:

Multifunction data-acquisition systems have been around for a long time as stand-alone instruments, plug-in cards, cabled computer peripherals, and embedded in systems. Such systems are often designed with separate ADCs, DACs, and digital I/O devices. Many microcontrollers include ADCs and DACs, but that locks you into using that device. The AD5592R from Analog Devices combines all of these I/O functions, letting you use one chip to design measurement-and-control functions into systems.

A data-acquisition system on a chip – [Link]

Highly Configurable 8-Channel ADC


by elektor.com:

A recent press release by Linear Technology announced the introduction of the LTC2373-18 low noise, high speed, 8-channel, 18-bit, 1 Msps, successive approximation register (SAR) ADC. The device is capable of operating from a single 5V supply and features a highly configurable, low crosstalk 8-channel input multiplexer, supporting fully differential, pseudo-differential unipolar and pseudo-differential bipolar analog input ranges. The LTC2373-18 achieves ±2.75LSB maximum integral nonlinearity for all input ranges with no missing codes at 18-bits and a typical SNR of 100dB for fully differential inputs and 95dB with pseudo-differential inputs.

The temperature-compensated onboard 2.048 V reference has a maximum drift of 20 ppm/°C and a singleshot capable reference buffer. For control the LTC2373-18 has a high speed SPI-compatible serial interface that supports 1.8 V, 2.5 V, 3.3 V and 5 V logic through which a sequencer with a depth of 16 may be programmed. An internal oscillator sets the conversion time, easing external timing considerations. The LTC2373-18 dissipates 40mW and automatically naps between conversions to reduce power consumption. This power saving feature is scaled in accordance with the sampling rate. A sleep mode is also provided which reduces power consumption to 300 μW during inactive periods.

Highly Configurable 8-Channel ADC – [Link]

DIY Digital AC Watt Meter


by electro-labs.com:

Have you ever been curious about the power consumption of an appliance? For example did you wonder how much it will cost you to leave your television in standby mode whole night? Or did you want to learn how much change your refrigerator settings will make on your electric bill? If your answer is yes, you can use a wattmeter to measure the power consumption of a device. In this project we are building one.

This is an AC Watt Meter which can measure the real power consumption of a device connected to the 230Vrms/50Hz mains line. The PIC microcontroller collects the voltage and the current information with the help of ADCs and then calculates the RMS voltage of the mains line, RMS current drawn by the device and the resulting average power consumption. All these information is then displayed on the dot matrix LCD.

DIY Digital AC Watt Meter – [Link]

Piconomic FW Library 0.4.2 released


by Pieter @ piconomic.co.za:

If you can beg, steal or borrow an Atmel ISP programmer, then you can use the Arduino environment to develop on the Atmel AVR Atmega328P Scorpion Board. An Arduino on Scorpion Board guide, Optiboot bootloader and example sketches have been added.

If you own an Arduino Uno board, you can now try out the Piconomic FW Library risk free without abandoning the creature comforts of the Arduino environment. You can use the existing Optiboot bootloader to upload code. I have added a getting started guide for the Arduino Uno. There are examples, including a CLI (Command Line Interpreter) Application that creates a “Linux Shell”-like environment running on the Arduino Uno so that you can experiment with GPIO, ADC, I2C and SPI using only Terminal software (for example Tera Term)… it is really cool!

Piconomic FW Library 0.4.2 released – [Link]

Review, Teardown and Experiments with a Keysight MSO-S Series 10-bit 20GS/s Oscilloscope

In this episode Shahriar does an extensive review and teardown of the Keysight (Agilent) MSO-S Series 10-bit 20GS/s Oscilloscope. This scope supports bandwidths up to 8GHz and 400M points of memory per channel. With hardware 10-bit ADCs as well as an ultra low-noise front-end, this scope offers an impressive dynamic range on all four channels. All scope features are software upgradable.

The teardown consists of a close look at the acquisition board and the system blocks diagram. Various elements such as the ADC structure, FPGAs, memory and the time-base are all examines. The scope offers a +/-12ppb time-base with a 100fs jitter noise floor. Some basic performance measurements are also presented such as noise and SFDR.

The wireless experiment shows the performance of the scope in demodulating very low-power signals on an RF carrier. A -75dBm 2.5GHs QPSK signal can be demodulated by the scope. The instrument can also demodulate a 16QAM signal in presence of an interfering signal which is 44dB higher in signal power. All demodulation experiments are performed using the Keysight VSA.

The backplane experiments demonstrate the scope’s capability to perform jitter and noise analysis on multi-gigabit serial links. The built-in equalization software suites are used to find the FFE coefficients and those coefficients are used to perform hardware equalization in an FPGA communication link.

Review, Teardown and Experiments with a Keysight MSO-S Series 10-bit 20GS/s Oscilloscope – [Link]

Monitor 15 contacts with one PIC input


by Benabadji Noureddine @ edn.com:

Several previously published Design Ideas and appnotes [1-4] show how to use many pushbuttons with a minimum number of inputs. They require an RC circuit where the timing can be measured to identify which pushbutton has been pressed, or an ADC input, with resistors forming a divider for each pushbutton pressed.

The following Design Idea shows another simple way to use up to 15 pushbuttons with only one I/O. The microcontroller chosen must contain an internal comparator with selectable values for the internal voltage reference VREF.

Monitor 15 contacts with one PIC input – [Link]