Sunday, March 22, 2015

Long day, little progress on the USB link to the fpga board


I ran into an anomalous behavior when trying to load the latest fpga bitstream onto the board's flash memory - I get an error writing the first block and it won't recover or write anywhere else. If the flash is hosed, I have two options. One is to erase it with an fpga load then try again. The other is to replace the chip on the board with a new one of the same type.

A second way to write to the flash is through the device web server provided in the SDK - but this too fails trying to write to the flash. I may have a bad device, although I might be able to reach it via the JTAG interface.

I am temporarily blocked by this problem and can't move on to test the link from the PC nor the SAC Interface box itself, unless I can load the bitstream out in the garage with the fpga board powered up from that point up until I run the tests. The  bitstream is only in volatile memory at the present, which makes it hard to test with the PC since the tools on this PC don't include any loader that recognizes the board.

I moved the device out to the garage, bringing both the surface pro and the laptop to combine the tools for loading the bitstream and for talking to the fpga logic I wrote. The nightmare of petty barriers continued - my laptop has to be extremely downlevel on Java in order to have the broken code of EMC's Documentum able to work properly, yet I can't run the SDK as it is just too old. The machine that runs the SDK is a fixed deskside machine in the den, too far away to easily relocate. Now on to try to get my Surface Pro able to run the right Java, libusb and other stuff needed just to put the bitstream on the fpga board. Arggggh. Hours wasted on petty issues like this.

By four in the afternoon, I finally was able to run the program on the PC but was seeing continual timeout in reads from the endpoint. Time to look closer at my fpga code,as I may have made a mistake in the modification of the sample designs.


I tested the 7000 lumen LED array light and it provided a nice clear light even in daylight, although I don't like having it pointing where I can look up into the lens as it is somewhat blinding. I think I will use a bounce screen above the lamp to reflect the upwards beaming light downward across the shed. I also need a better enclosure for the LED power supply which is a naked PCB right now.

I have a photography umbrella reflector coming which will be perfect for the installation. I moved the light where it should go, but in the process broke one blade off the rotary cooling fan. I will replace this as it causes way too much vibration and noise in its damaged comdition. 

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