MirceaDabacan

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About MirceaDabacan

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  1. In fact, I recommend either of the below: - use a speaker with Pmod Amp2 (without amplifier) - use Pmod I2S2, with external amplifier and speaker.
  2. Hi Jonathan, PmodAmp2 is a class D audio amplifier. Supplied with 3.3V (in conjunction with Basys 3), it generates an output voltage up to 6.6Vpp. The output signal will consist in only 3 levels: -3.3V, 0V, +3.3V. The load circuitry should filter the pulse modulated signal to an audio analog signal. The high input impedance of the speaker amplifier will not allow a high current. The voltage amplitude can eventually damage the speaker amplifier. Please check if this withstands a voltage of +/-3.3V (6.6Vpp). Reducing the “volume” of the digital signal would not help: the amplitude of the pulses will not decrease, just the duty factor… The next question is: how will you generate the signal to drive the Pmod Amp2. I see two possible options: Using an AD convertor Pmod (ex. Pmod DA2). The PmodAmp2 would be cascaded into Pmod DA2. Using a PWM modulator. In both cases, you can adjust the volume by multiplying the digital sample values with a “volume” constant.
  3. in the http://digilentinc.com/Data/Products/ANALOG-DISCOVERY/Discovery_TRM_RevC_1.pdf, page 12, the Vin range is defined for Low Gain and High Gain. The ADC has 14 bit. The vertical resolution is (Vin Max - Vin Min)/(2 ^14). Obviously, the accuracy is worse than that. It depends on calibration, temperature, probes, etc. The horizontal resolution is the sample rate, displayed on to of the scope screen. (8192 samples at xxx kHz/xxx us)) It depends on time scale. In fact, the scope always samples at 100MHz/sec, but decimates or averages multiple samples for storing, when needed.
  4. A classical programmable (desktop) power supply allows users to set a voltage and a current limit, unlike fixed power supply (like a phone charger) which have fixed voltage and current limit. Knobs, buttons and displays on the power supply panel are enough to say that the voltage and current are programmable. Some supplies have additional communication interfaces (USB, RS232, IEEE488, etc.), allowing a PC to take control from the panel and set the voltage and current limit. Obviously, a program needs to run on the PC to send the appropriate commands via the interface. With the EE board, the HW panel is replaced by the WaveForms GUI, but the features are the same: you set a voltage (limit) and a current (limit). The actual relation between the voltage and current is given by the load; if resistive, then U=R*I. Either U or I reach the "programmed" limit, setting the actual behavior. EE board and WaveForms offer more that simple "programmability": ONCE: you have the equivalent of a HW interface (like RS232 or other) - this is the API set provided by the SDK. You can use that to control the voltage from a user application - similar to whatever PC program you would use to send RS232 commands. SECOND: you can actually generate a waveform (with specific amplitude and frequency limitations). This feature is completely original; I did no see that on other power supplies. This in fact transforms the power supply into an AWG with huge current capabilities. To use that, you need to add power supplies as channels in the AWG instrument.