This has been on my list of things to do for a while and represent a few challenges. Chips like AD9851 contains a full DDS that interface to a MCU on one side and give 3.3V signals on the other side. I have yet to decide wherever to use AD9851 or something else, butAD9851 is…
This illustrates the BasicPI Firmware Stack in progress. What I always do in embedded applications is to make a “standard” main.cpp as follows: void AppInit() { // wire hardware } int main() { AppInit(); // start OS } A team I worked in years ago agreed on this standard so we should…
This illustrate the main functionality I want to achieve. The DDS can generate waveforms as well as more classic squares, triangles, sinus etc. I would like a signal that can be amplified to +/-20V and given a base offset anywhere within that range. The blue line illustrate a more classic square signal starting at…
I think I can achieve a decent function generator by combining AD9851, AD8008 and AD5231 as shown above. AD8008 is an amplifier with 650Mhz bandwidth and it uses a resistor for Gain adjustment – I think I can use AD5231 for that purpose. The Voltage input is max 12V so I should in theory be…
I showed the MOSFET driven resistor array earlier and while searching for digital potentiometers I found 2 that are SPI based on 10K. One is the MCP41010 with 255 steps, but the one I really liked is the new AD5231 with 1024 steps. They exist in 10K, 50K and 100K versions and provide a far…
Assuming I create one Hat with AD9851 and a second with an analogue, programmable PSU and a 3rd with an amplifier this project suddenly becomes very realistic. I doubt that I can get all I need on one Hat and an analogue low noise +/- 24V PSU is actually so awesome that I would…
This weird circuit is a programmable, analogue PSU. It is basically only a LM317 and an array with resistors and MOSFET’s so I can program the voltage out by selecting a combination of 10 resistors. This is not straight forward, but I can at least Select 10 preset values. In addition I use an ADC…
I need a function generator and I like AD9851. What I really would like is a Function Generator Hat with programmable +/- voltage like the diagram below: This is not impossible, but the DDS, Amplifier and Programmable PSU on a small Hat is not realistic. Or – well – I need to think about that…
I bought a kit with AD8950 earlier that I consider using to create a programmable function/audio generator. AD8950 can generate waves to very decent frequencies and cost ca 10.- USD. AD8951 cost a bit more and it is straight forward to create a DDS/DAC based on these. But, I also need a driver stage where…