The ADC ADC data acquisition component is a monolithic CMOS device with an 8-bit analog-to-digital con- verter 8-channel multiplexer and. ADC ADC – 8-bit Microprocessor Compatible A/D Converters With 8- Channel Multiplexer, Details, datasheet, quote on part number: ADC The ADC/ADC Data Acquisition Devices (DAD) implement on a single chip most the elements of the stan- dard data acquisition system. They contain.
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Note that it can take up to 2. At clock speeds greater than that the user must make certain that enough time has passed since the ALE signal was pulsed so that the correct address is loaded into the multiplexer before a conversion begins. All control signals should have a high voltage from Vcc – 1. It is acc0809 control signal from the FPGA, which tells the converter when to start a conversion. The OE signal should conform to the same range as all the other control signals. The start signal should conform to the same range as all other control signals.
Bottom rail of Reference voltage.
This means that in order to get it to work, there is a total of seven control signals that must be sent from the FPGA. If Vcc and ground are used as reference voltages, they should be isolated by decoupling with a 1 microF capacitor. It goes low when a conversion is started and high at the end of a conversion. Top rail of Reference voltage. It is recomended that the source resistance not exceed 5kohms for operation at 1. The signal goes avc0809 once a conversion is initiated by the start signal and remains low until a conversion is complete.
This means that an entire conversion takes at least 64 clock cycles. There are 8, 8 clock cycle periods required in order to complete an entire conversion. It is the LSB of the select lines. The other files are enabled register, a register, and a multiplexer. Once loaded the multiplexer sends the appropriate channel to the converter on the chip. The signal can be tie to the ALE signal when the clock frequency is below kHz.
Be sure to consult the manufactures data-sheets for other chips. Clock The clock signal is required to cycle through the comparator stages to do the conversion. See table 1 for details.
Modification to the source code are required to dagasheet more than just four channels. The source code provided was used to control an ADC where only 4 inputs were used, therefore, ADD C is tied to ground adx0809 so are the datashert inputs.
National Semiconductor – datasheet pdf
This is a bit of the digital converted output. Table 2 provides a summary of all of the input and output to the chip. The ALE should be pulsed for at least ns in order for the addresses to get loaded properly. You will also need to download multiplex. The source datashedt remain stable while it is being datasheeh and should contain little noise.
In this implementation the OE signal is pulsed high one clock cycle after the EOC signal goes high and remains high until the data is safely stored into the desired register in the FPGA. Control signal from FPGA. It is the MSB of the select lines. Signal from the ADC. Address Lines Because the chip has an 8 channel multiplexer there are three address select lines: It can be tied to the Start line if the clock is operated under kHz.
All of the signals are explained adc809.
ADC Datasheet(PDF) – National Semiconductor (TI)
Up to 72 if the start signal is received in the middle of an 8 clock cycle period. This is an address select line for the multiplexer. Like the ALE pulse the minimum pulse width is ns. It is the Second bit of the select lines.
Source code The source code consists of a few of files. Users can look for a rising edge transition.
C is the most significant bit and A is the least. A, B, and C. The minimum pulse width is ns.
The source resistance must be below 10kohms for operation below kHz and below 5kohms for operation around 1. For a quick reference refer to table 2. Start The purpose of the start signal is two fold. It is a pulse of at least ns in width. There are a couple of limitations that follow: The following control signals are used to control the conversion.
Begin by downloading the files into your desired destination directory and then compile them in this order. Unfortunately you cannot just hook up analog inputs to an ADC and expect to get digital outputs from the chip without adding control signals.
The ac0809 frequence of the clock eatasheet 1. As with all control signals it is required to have an input value of Vcc – 1. This means it must remain stable for up to 72 clock cycles.