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Updated references to work with the ADC12 and the ESCAPE platform

The c language and analog interfacing: your task

This lab covers the basic principals behind Analog to Digital Conversion, as well as the basics of programming in C. You are expected to have some background in C from class, but if you are confused, see this basic reference .

  1. Using Code Composer Studio 5, write a C language program turning your ESCAPE Platform into a simple 10 level light meter. Your program should divide the 0-3.3V input range of the ADC into 10 zones, and then output from a 0 to a 9 on the LED display depending on the input voltage. IN GENERAL, DO NOT EXCEED AN INPUT VOLTAGE OF 3.3V (You don't have to worry about this during this light sensor lab). You will damage your circuits and destroy your MSP430 if you measure a raw voltage greater than 3.3V though. Assignment Details

The adc and "c" through a practical example

Interfacing with the analog world: the adc

ADC's play an incredibly important role in digital electronics and DSP. ADC stands for A nalog to D igital C onverter, and it does exactly what you would expect it to. It samples an external voltage, and then converts that voltage to a binary number compared to the reference voltage range from Vdd to Vss. (In plain English terms, the ADC samples what fraction the input is of some maximum allowed reference voltage.) The ADC's result gets written to a memory mapped register, where the programmer can access it and use it in his or her code.

An ADC has a finite voltage range it can safely convert (usually related to its power supply range, but not always). The precision of the converted sample is related to the number of bits used by the ADC. More bits means more precision (more finite "slots" into which the infinitely variable analog single can be quantized) and a lower "quantization error." To learn more about error and ADC, see this except from the Introduction to Electrical Engineering course notes . ADC's also have a maximum sampling rate specification (how frequently the ADC can make a conversion), but in this course we will be sampling very low frequency signals, so we won't need to worry about it.

The msp430 adc

The MSP430 F5637 has one 16 channel 12 bit 200Khz ADC. ADC channels allow the single ADC to select between several different signals (such as two different analog inputs on different GPIO pins) like an analog multiplexer. In the F5637, channels 1-8 are connected to the 8 P6 GPIO pins, and channel 10 is connected to the chip's internal temperature sensor.

For this lab, we will configure the ADC to use the internal 3.3 Vdd as the reference voltage.

  • A voltage of 3.3V would result in the ADC register holding 1111 1111 1111 (0x0FFF)
  • A voltage of 0.0V would result in the ADC register reading 00 0000 0000 (0x0000)
  • A voltage of 1.65V would result in the ADC register reading 0111 1111 1111 (0x07FF)
  • The ADC will have a sample resolution of 3.3V/4096 [Voltage Range/2 #Bits ], or .00081 Volts.

The ADC is a peripheral device, so it operates independently from the CPU. It has several operation modes (configured by writing to its control registers).

A device that can operate independently from direct CPU support and control. Peripherals often rely on interrupts to notify the CPU when they have completed some given task or need attention, and use independent control registers for configuration. The ADC 12 is a peripheral, as well as the MSP430's UART (serial controller) and timers.

    Adc12 operation modes

  • Single Sample and Hold-- the ADC12 will start a conversion when triggered by the CPU. After that conversion, it will hold the converted value in the ADC12MEMx registers and automatically go into sleep mode until signaled to begin another conversion. We will mostly use this mode.
  • Sequence of Channels Sample and Hold-- the ADC12 will convert a series of different channels once, and store the result to ADC12MEM.
  • Repeat Single Channel Mode-- it will continuously sample on channel, continuously updating the ADC12MEM register.
  • Repeat Sequence of Channels Mode-- the ADC will continuously sample through a series of channels.
The MSP430's ADC 12 also has a built in memory controller. We won't be using it, but it becomes important when using the repeat modes. The memory controller can automatically write the ADC data into main memory as conversions finish, bypassing the CPU.

Questions & Answers

anyone know any internet site where one can find nanotechnology papers?
Damian Reply
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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