Mark I Interface Usage Notes Glenn Jones July 13, 2006

I have included the Windows USB drivers and some Matlab routines that I used to test so you can try those out. I don’t have an interface spec for the raw commands yet, but the commands and data format can be easily figured out from the PIC code and the Matlab routines. I modified the PIC code slightly so now it doesn’t miss the falling blanking signal even if it is in the middle of transmitting data.

Linux stuff Here are some application notes giving programming advice. The particular chip I used is the FT232R. There are two types of USB drivers, Virtual Com Port (VCP) and direct (D2XX). I have been using the VCP driver exclusively without trouble, though you may want to look into the D2XX if you think it may help. I have not tried any interface stuff under linux. The drivers are located here: The Windows VCP driver I included is NOT the same as the one on the website. I modified it so that when you set the virtual com port to 600 baud, it actually sets the chip up to do 250kbaud. This is explained in this appnote: 05_BaudRates.pdf I think probably a similar thing can be done under linux. 05_BaudRates.pdf The PIC UART is configured for 250kbaud

Starting up Matlab When you get the USB driver installed correctly using the drivers I included, check to see which COM port it is assigned to. Edit init.m to reflect this COM port. init.m sets up the COM port object ‘I2Cser’, which must be the first argument to all of the other routines. (you can name it something else if you like) To test communications, try sending: set_atten(I2Cser,2,’FF’) You should see something like this: >> set_atten(I2Cser,2,'FF') cmd = `S02FFA1~ ans = `S0~ If not, try sending a couple more times.. I find it takes sending a few commands at startup to get the UARTs synched up. At the end of the Matlab session, run closedown.m to free the COM port. If you accidentally clear I2Cser, the instrfind command is very useful.

Matlab commands I added comments describing usage of all the useful Matlab routines, thus look there to see how to use them. The main commands you probably want to use for testing are: SetPICint – Set the PIC to generate a blanking signal SetExtBlank – use an external blanking signal on the BNC connector ReadFor – take data for x seconds

A typical matlab session might look like this: >> init % setup the serial port >> set_atten(I2Cser,2,'FF')% Select the 1000 MHz filter and set the attenuator to 0dB cmd = `S02FFA1~ ans = `S0~ >> set_atten(I2Cser,2,'01')% Select the 500 MHz filter and set the attenuator to 16 dB cmd = `S020075~ ans = `S0~ >> SetPICint(I2Cser,0.01,0.1); % set the pic blanking to 10 ms high, 100ms integration cmd = `PFFB3FCF4B4~ % FYI this is what the command to the pic looks like status = `P~ % successful reception >> [tp st] = ReadFor(I2Cser,1); % Tell the pic to give you 1 second worth of data cmd = `IFF35~% Random inner workings cmd = `I0009~ status = Vlid ¤Ù ¦\ `I~ cmd = `I0009~ status = `I~ ans = Dataset size: 547 Found 8 headers % This means that it received 547 bytes which it parsed into 8 sets of 8 % channels worth of total power >> plot(tp(3,:))% look at the results for a channel. >>[tp st] = ReadTPn(I2Cser,10) % Tell the pic to give you the data from the next 10 blanking signals it sees cmd = `I0A1A~ ans = Dataset size: 683 Found 10 headers % found all 10 >> SetExtBlank(I2Cser)% change to external blanking mode cmd = `XB8~ status = `X0~% indication that the command was understood >> closedown% All done, so clean up the COM port