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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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Modification to the source code are required to use more than just four channels. A, B, and C.

National Semiconductor – datasheet pdf

The source must remain stable while it is being sampled and should contain little noise. The following control signals are used to control the conversion. This is an address select line for the multiplexer. Source code The source code consists of a few of files.

Signal from the ADC. It is a pulse of at least ns in width. See table 1 for details. The signal goes low once a conversion is initiated by the start signal and remains low until a conversion is complete. Note that it can take up datashret 2.

The maximum frequence of the clock is 1. The voltage level that, when received as an input, will output “” to the FPGA.

You will also need to download multiplex. The minimum pulse width is ns. At clock speeds greater than that the user must make certain that enough time adc08009 passed since the ALE signal was pulsed so that daatsheet correct address is loaded into the multiplexer before a conversion begins. It goes low when a conversion is started and high at the end of a conversion.

It can be tied daasheet the Start line if the clock is operated under kHz. Top rail of Reference voltage. Address Lines Because the chip has an 8 channel multiplexer there are three address select lines: Be sure to consult the manufactures data-sheets for other chips. The OE signal should conform to the same range as all the other control signals. Up to 72 if the start signal is received in the middle of an 8 clock cycle period.


National Semiconductor

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 start signal should conform to the same range as datasehet other control signals. The ALE should be pulsed for at least ns in order for the addresses to get loaded properly.

The maximum clock frequency is affected by the source impedance of the analog inputs. Begin by downloading the files into your desired destination directory and then compile them in this order.

It is the MSB of the select lines. It is recomended that the source resistance not exceed 5kohms for operation at 1.

In this implementation the OE signal is pulsed high one clock cycle after the EOC acd0809 goes high and remains high until the data is safely stored into the desired register in the FPGA. Bottom rail of Reference voltage. Once loaded the multiplexer sends the appropriate channel to the converter on the chip. The other files are enabled register, a register, and a multiplexer. The signal can be tie to the ALE signal when the clock frequency is below kHz.

Control signal datashwet FPGA. If Vcc and ground are used as reference voltages, they should be isolated by decoupling with a 1 microF capacitor. It is the LSB of the select lines.

Table 2 provides a summary of all of the input adc00809 output to the chip.


The source resistance must be below 10kohms for operation below kHz and below 5kohms for operation around 1. Like the ALE pulse the minimum pulse width is ns.

Analog to Digital Converter – ADC/ADC

The ADC stores the data in a tri-state output latch until the next conversion is started, but the data is only output adv0809 enabled. It is the Second bit of the select lines.

The clock should conform to the same range as all other control signals. This means it must remain stable for up to 72 clock cycles. There are 8, 8 datsheet cycle periods required in order to complete an entire conversion. All control signals should have a high voltage from Vcc – 1.

That is because ADCs require clocking and can contain control logic including comparators and registers. On the rising edge of the pulse the internal registers are cleared and on the falling edge of the pulse the conversion is initiated. C is the most significant bit and A is the least. Users can look for a rising edge transition. The source code provided was used to control an ADC where only 4 inputs were used, therefore, ADD C is tied to ground and so are the unused inputs.

Start The purpose of the start signal is two fold. It is a control signal from the FPGA, which tells the converter when to start a conversion. As with all control signals it is required to have an input value of Vcc – 1. This is a bit of the digital converted output. This means that an entire conversion takes at least 64 clock cycles.