July 15, 20169 yr I wrote a Python implementation with full GUI on Raspberry Pi 3 with touchscreen, which works fully on the old I2C boards balanced with balance control like the one I did for 4D systems touchscreen. I will take the next few weeks to incorporate that into a full web server implementing a RESTful API. However, just to make sure, is the pdf Kevin posted in the beginning of the thread the correct wiring for the relays? As in first 4 flipped compared to the second 4, etc. Also, the MAX4820s are daisy chained so do you just write commands in series? I have to implement bit banging SPI because the touchscreen uses the hardware SPI
July 15, 20169 yr First 4 relays are opposite polarity from the second 4 on the max4820 boards. Yes all 4 of them in series, so 32 bits to write all relays.
July 20, 20169 yr Thanks, that helped a lot. I'm having problems with just pin OUT5 of all 4 MAX4820s for some reason, it won't toggle the voltages like all the other pins. What do you think I might have done wrong? Seems too specific to just be a poor soldering job, thought that's always a possibility. Will start probing more in-depth with a DMM tomorrow.
July 22, 20169 yr On 7/19/2016 at 11:23 PM, mypasswordis said: Thanks, that helped a lot. I'm having problems with just pin OUT5 of all 4 MAX4820s for some reason, it won't toggle the voltages like all the other pins. What do you think I might have done wrong? Seems too specific to just be a poor soldering job, thought that's always a possibility. Will start probing more in-depth with a DMM tomorrow. I've only built the prior version of the smaller board (before the relays were flipped). Everything works well on that version. I've got the latest board ready to build. Just need some time. Let us know if you get it working.
August 2, 20169 yr Server volume test is up and running for the i2c boards, here is screenshot of test volume and balance control Web page and i believe it should work for almost all browsers and devices. I will try to get modernizr working just in case. Also will finally start troubleshooting spi boards now and add some other cool features...
August 28, 20169 yr Got web sockets working so now temperature or any other sensor data can be shown in real time without having to make any client server requests. I have the i2c ADCs and temperature sensors low level code, just need to incorporate them as right now the data array is generated from integer random generator. The latency is pretty variable while on my phone, though, it's more stable on my laptop for some reason. Potentially can make a crude WiFi oscilloscope! Edit: anyone have experience with bit banging spi for writing to SD card? Edited August 28, 20169 yr by mypasswordis
October 11, 20169 yr I finally have a simple "ish" solution for the controller on the digital attenuator. I developed two boards. The first is a RK50 to Stepped Attenuator adapter board. It is the same size as the Stepped Attenuator board and will fit into an RK50 pinned board. The second is a controller board that supports a motorized POT with IR similar in function to AMB's controller, but as a smaller module with no built in display. A display could be added via the headers (I2C or SPI). It has an ATMEGA328P similar to the Arduino UNO or mini pro. The board is 1" x 2.5" and extends about a half an inch past the motorized POT. It can be programed via a programmer or via the FTDI USB boards. I need to double check everything, but I'll put an order in soon and test to make sure everything works ok.
October 15, 20169 yr Managed to squeeze the code in ATtiny85. I do think it will be able to control the balanced digital attenuator... ...maybe.
October 15, 20169 yr I was just looking to see if it supports SPI. Good and bad news... The chip supports it but there doesn't seem to be libraries written for this chip according to spark fun. There may be some user libraries out there.
October 16, 20169 yr Here's a mini version of the attenuator controller board without a motorized pot. The board is 1" x 1.65".
October 28, 20169 yr Got the simple one built. I burned the boot loader, but was waiting on the FTDI stuff so I can easily program it.
October 29, 20169 yr Very cool! So that thing by itself can control the digital attenuator if you don't want to bother with display, etc.?
October 29, 20169 yr Yes. It's a standard linear pot rather than an encoder, so the volume is set by it's position. I have an I2C header if you want a display, but it's not necessary.
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