After a very frustrating weekend, I am pretty confident I have the worst of the integration problems behind me. The Embedded Adventures board is a very nice board but did take the choice of SPI or I2C out of my hands. It was designed to be I2C only. Not a problem. The Arduino does I2C.<\/p>\n
So I hooked up the break out board to my Arduino UNO and started to write some basic “Wire Library” code. How hard could this be? Well after the first day, I would say pretty hard. Turns out the AS3935 has some pretty stringent demands for reading and writing registers. Mostly, when turning around the bus, you must use a “Repeated Start” and not a more normal Stop and Start sequence. After I figured that out, I was able to realize that the Wire library does support that, but not in so many words. After Day one, I at least was getting some ACKs from the device address part of the bus transfer.<\/p>\n
After day two, I was able to read and write most registers except register 0x00. This one kept giving me a NAK when I sent over the device address for the read after I had sent over the register address in the write part of the transaction. Much aggravation because sometimes it would work and other times not.<\/p>\n
In the mean time, I have exchanged numerous emails with the Embedded Adventures people in the UK. They must never sleep and take days off over there because I was getting very fast turn arounds on the questions I was asking. The upshot is that they had issues as well with register 0x00. So with that in mind, I did a careful survey of the issue and discovered what must be an “undocumented feature”. Reading register 0x00 will always NAK you till such time as you read a different register. After that you can read and write any and all legal registers. I have sent out yet another email to the AMS people in Austria asking them about this issue and any other errata they might like to share.<\/p>\n
At the end of day three with the low level communication finished, I was able to get the unit to self calibrate and to sit in listen mode. Further more, I was able to get it to respond with “disturber (not lightning)” reports when I generated sparks in the area. Without the awfully expensive lightning simulator from AMS, I will now have to sit around and wait for a storm. That might be many months from now.<\/p>\n
But now with this off my plate (its been a running project for more than two years) I can get back to the AVC. Just so happens that I got two thermo electric coolers in the mail over the weekend just waiting to try to temperature stabilize the IMU and to characterize it for hard and soft magnetic properties.<\/p>\n","protected":false},"excerpt":{"rendered":"
After a very frustrating weekend, I am pretty confident I have the worst of the integration problems behind me. The Embedded Adventures board is a very nice board but did take the choice of SPI or I2C out of my … Continue reading