Electronic scales are widely used in kitchens and bathrooms because they can quickly make accurate weight measurements.
A load sensor called a load cell is used for weight measurement. Because the output voltage of this sensor is very small, it is amplified by an operational amplifier (op-amp) and input to an A/D converter. A microcontroller (MCU) converts the signal to weight based on the conversion results of the A/D converter and displays it.
Renesas offers a lineup of microcontroller products for meeting their customers’ needs, such as the RL78/L1x, 78K0/Lx3, and R8C/Lx series with built in LCD driver for designing small and inexpensive models. For highly precise measuring, they offer the 78K0/Lx3, the H8/38086R group, the RX21A group, and other with built-in high precision ΔΣ (delta-sigma) A/D converter.
Renesas MCU for Electronic Scales - [Link]
The LTC2338 fully differential 1Msps SAR ADC family offers a wide ±10.24V true bipolar input range for high voltage industrial applications. The proprietary internal reference buffer maintains less than 1LSB error during sudden bursts of conversions, enabling true one-shot operation after lengthy idle periods. The internal reference can be overdriven to interface to a range of signal levels that swing above and below ground. The LTC2338 family eliminates complicated circuitry required to interface true bipolar signals to ADCs, and provides a compact solution for easy interfacing to 1.8V to 5V serial logic. The LTC2328 offers similar performance with a pseudo-differential input.
LTC2338-18 – 18-Bit, 1Msps, ±10.24V True Bipolar, Fully Differential Input ADC with 100dB SNR - [Link]
This Instructable will teach you how to use the Arduino Analog ports. johnag @ instructables.com writes:
Digital Voltmeters (DVMs) are a special case of Analog to Digital converters- A/DCs.- they measure voltage – and are usually a function of a general purpose instrument called a Digital Multimeter( DMMs), commonly used to measure voltages in labs and in the field. DMMs display the measured voltage using LCDs or LEDs to display the result in a floating point format. They are an instrument of choice for voltage measurements in all kinds of situations. This instructable will show you how to use the Arduino as a DC DVM (Direct Current Digital Volt Meter).
Make a Mini Arduino programmable 4 channel DC-DVM - [Link]
by Claude Haridge:
Microcontroller-based products sometimes require rotary switches. As many microcontrollers have an onboard ADC, it is easy to replace the rotary switch with a low cost potentiometer, when a rotary switch is too expensive or unavailable.
Although digitizing a potentiometer setting to act like a switch requires only a few instructions, an immediate problem is that instabilities in value occur at the switching threshold between one value and the next due to electrical or mechanical noise. The solution is to introduce upper and lower hysteresis thresholds about each transition so that the potentiometer needs to move beyond a threshold before another switch state is validated. For every updated switch state, another pair of thresholds replaces the previous. In this manner, the hysteresis provides clean switching between states.
Replace a rotary switch with a potentiometer - [Link]
By Stephen Evanczuk
For circuits relying on lithium-ion cells, determining the amount of charge remaining in a cell requires specialized techniques that can complicate the design of energy-harvesting applications. Engineers can implement these techniques with MCUs and ADCs normally used in these applications, but at the cost of increased complexity. Instead, engineers can easily add this functionality to existing designs using dedicated “fuel-gauge” ICs available from manufacturers including Linear Technology, Maxim Integrated, STMicroelectronics, and Texas Instruments.
Determining the state of charge (SOC) in lithium-ion batteries is essential yet challenging due to the great variability in capacity not only across different cells, but also in the same cell. As a Li-ion cell ages, it loses its ability to store charge. Consequently, even if fully charged, an older cell would deliver usable voltage for a shorter period of time than a newer cell. With any Li-ion cell, SOC varies greatly depending on the temperature and discharge rate, resulting in a unique family of curves for any particular cell (Figure 1).
Fuel-Gauge ICs Simplify Li-Ion Cell Charge Monitoring - [Link]
John Boxall over at Tronixstuff has a series of Arduino tutorials. This chapter fifty-three of a series will show you how to use the TI ADS1110 16-bit ADC with Arduino:
Moving on from the last chapter where we explained an 8-bit ADC, in this instalment we have the Texas Instruments ADS1110 – an incredibly tiny but useful 16-bit analogue-to-digital converter IC. It can operate between 2.7 and 5.5 V so it’s also fine for Arduino Due and other lower-voltage development boards. This is a quick guide to get you going with the ADS1110 ready for further applications.
Tutorial – Arduino and the TI ADS1110 16-bit ADC - [Link]
Active analog filters can be found in almost every electronic circuit. Audio systems use filters for frequency-band limiting and equalization. Designers of communication systems use filters for tuning specific frequencies and eliminating others. To attenuate high-frequency signals, every data acquisition system has either an anti-aliasing (low-pass) filter before the analog-to-digital converter (ADC) or an anti-imaging (low-pass) filter after the digital-to-analog converter (DAC). This analog filtering can also remove higher-frequency noise superimposed on the signal before it reaches the ADC or after it leaves the DAC. If an input signal to an ADC is beyond half of the converter’s sampling frequency, the magnitude of that signal is converted reliably; but the frequency is modified as it aliases back into the digital output.
Designing active analog filters in minutes - [Link]
Analog-to-digital-conversion (ADC) is required in Embedded Systems to deal with various analog world parameters such as current, pressure, motion, temperature, etc. An ADC is an electronic system or a module that has analog input, reference voltage input and digital outputs. The ADC convert the analog input signal to a digital output value that represents the size of the analog input comparing to the reference voltage. It basically samples the input analog voltage and produces an output digital code for each sample taken. This application note from Atmel describes the fundamental concepts of ADC and the associated parameters that determine the performance and accuracy of the ADC’s output.
Understanding ADC parameters for accurate analog-to-digital conversions - [Link]
This project describes an Arduino-based FM transmission using the KT0803K Digital Stereo FM Transmitter Radio-Station-on-a-Chip. The KT0803K device is designed to process high fidelity stereo audio signal and transmit modulated FM signal over a short range. It features an on-board 20-bit audio ADC and supports standard I2C interface for frequency setting and power control. [via]
DIY FM transmission station using Arduino - [Link]
“miceuz” have set up this little experiment to gain a better understanding how does a SAR analog to digital converter work. Go to http://wemakethings.net/2013/02/25/how-does-adc-work/… for more info and Arduino code.
How does an ADC work? - [Link]