We can finally control the leds one by one with the gumstix through the gpmc and the fpga and play a little bit with our system.
As usual, big thanks to Alexis for the help.
Now it’s time for the breakfast and the coffee in the students’ home !
We worked on the FPGA this last days.
While I was working on controlling the LED driver, Felix and Sylvain worked on the communication with the gumstix. The news are good :
- the communication between gumstix and FPGA is now working. But, the module for the communication must be modified because, in our real system there will be 2 clock : the FPGA clock and the gumstix clock (just for the data transmission). Felix and Sylvain have finished to implement this new architecture but, it must be tested.
- the control of the LED driver is perfect: we can now turn on all the LED on the propeller, choose the color and the intensity
The next steps are controlling the LED thank to the gumstix and, writing in the external RAM.
The FPGA is now able to do a write access with the GPMC (a read access is not possible for the moment). While Sylvain will work on the reading problem (there are some problems with nOE signal … ), I will test some final modules on the FPGA. All modules are written (with the new calculation flow) and, most of them (but not all for the moment) are tested on simulation. Today, I want to test on the FPGA some modules : ram controller and ram switch modules.
Today we succeed in sending a data in the gpmc bus that we have read with the fpga and sent to the ram. In the 16 bits, one was false, so we still have some signal issue but it’s already a good news !
That’s it, after some problems with the power supply and the SYSEN signal, our Gumstix is finally working on our expansion board and we succeed to ssh through the wifi on it.
Now we have to make work the gpio communication between the gumstix and the fpga (mainly for the jtag) to validate the proper functionning of the board and the fpga. Then we will try to hack the gpmc protocol to make it work without the CS (next to our nCS0 issue).
We finally finished our PCBs. I took care of the pinout and the placement, then I started the routing in trying to put in one PCB all the logic the power supplies and the leds. But the routing in the center is very complicated and loaded (with the leds and the fpga in a same place and constraints with some heavy components), that would have forced us to get a 4-layers PCB. Which with a 50cm long PCB would have cost an outrageous price.
So we split it in 2 PCB, one with the logic and the power supplies, Sylvain has dealt with.
And one with only the leds and leds driver, Jeremy has dealt with.
During this time I started to deal with Gumstix and install a Debian armhf on it. I’m currently operating the WiFi to make it works properly and in access point with a dhcp and a web server inside.
Today we make an experiment with the Gumstix. Our problem was to know if in turning at 1000rpm in a ventilator the WiFi will work correctly.
The first was to get a wireless power source to the Gumstix.
We got a lot of problems with that. First of all, the power connector of our Tobi expansion board is damaged (thanks to Copterix ) which cause a lot of reboot at any movement… We solved this with a lot of gaffer.
Secondly our hacked connector (with sticky tape) for the battery was not very well either and caused some trouble. Thanks to the PACT project which order a lot more than necessary 9V battery connector we improved our power line.
And last problem for the power, our board was rebooting in loop before we had a chance to login in… Simple problem but hard to guess, our battery didn’t deliver enough current. It was easily solved with a second battery in parallel.
Now, add a lot of gaffer to secure into place the batteries, the Gumstix and the antenna and we’re ready.
Of course, Murphy’s law requires, at this exact time the Gumstix decide to no longer properly boot and the WiFi to stop working. But with a little of black magic that finally worked and we have done our tests.
Our ventilator was missing of power and can’t get to its maximum speed (~1100rpm) with our board mounted on it (we could do better with a better balancing of the weight). But at the speed that we reach we succeed to had no loss of bandwidth (to confirm with a faster ventilator) which is a good news.
The bad news is that even placed on a table at 20cm from the computer we can’t do better than 1.5MB/s of transfer rate in WiFi (and 3MB/s in ethernet…) which is some kind of disappointing.
The practical works on the stm32 board is finally finish and complete. There is now just to finish the PCB for Wednesday.
Last friday there was the communication challenge that went well and took us the entire day.
Now for Rose Ace we have to finalize our architecture. So we’re working on a Gumstix this week-end to check that it has enough computing power for our application and that WiFi reception is good, even in a ventilator running at 1000rpm.
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