Finally got SPI working with MAX2871

A project log for Microwave Transmitter

30 - 6000 MHz synthesizer with power amplifier

PeroPero 07/22/2017 at 21:142 Comments

It really took a long time to get the damn MAX chip working. Although I made it set MUX line high or low, I couldn't make it talk to me via SPI. On the scope, this line looked like nonsense:

In the process of investigating, I managed to burn 3 Teensy boards and 2 MAX chips. Don't ask how. I consulted tech support of Maxim Integrated as well. They were really friendly and prompt reacting (thanks Mohammed). But, before I got the answer from them, I decided to try one thing. 

MUX bits are distributed in two registers. MUX[3] is in reg 5 while MUX[2:0] in reg 2. My initial code was writing reg2 first and reg5 later. For no clever reason, I decided to switch the order of writing. Guess what? Problem solved. 


I'm using SPI read to get some data out of MAX2871. These are for chip temperature, VCO tuning voltage, and autoselected VCO number. During the development I found out that ADC that reads VCO voltage and temperature must be set and reset after each readout. Otherwise, it won't read properly. 


Tegwyn☠Twmffat wrote 07/23/2017 at 09:06 point

Well done - you got their in the end. I managed to burn out one of my expensive VGA chips yesterday - a small pool of liquid could be seem erupting from the bottom right corner. I don't think this is normal :)

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Pero wrote 07/23/2017 at 20:30 point

thanks, but, what?? liquid coming out of chip??

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