Tue., Apr. 3rd (PM)

The lab has been BAKING HOT in the afternoon for the last couple of days.  It's hot outside, but still...  Someone needs to complain to FAMU Physical Plant - they need to crank up the A/C in the building.  In the meantime, I texted Antony asking if he could remotely shutdown the Xserve nicely.  I really think we need to start turning off all of the major computing systems when we're not actively using them.

My plan for today:  Continue putting together the new, longer jumper wires for the test setup so that they can be mounted on the main board (and still remain functional) as soon as the ME students bring it back in.

I'm wrapping my makeshift "connectors" (really, just bundles of single-pin sockets) in electrical tape to hold the wires in the canonical order I'm defining.  (Based on the signal order on a DE9 connector.)

My present color code is as follows, for the 

• (#1) Red:        Host   Rx <-- Wi-Fi Tx
• (#2) Blue:       Host    Tx --> Wi-Fi Rx
•    Yellow:       Host DTR --> Wi-Fi DSR (autorun)
• Not presently included - instead hotwire on Wi-Fi board from J2 pin 27 (+3V out).
• (#3) Black:     Host GND --> Wi-Fi GND.
• Presently Wi-Fi is also grounded to PC via USB port.  Ultimately, need to ground it directly to Samad's power distribution board.
• (#4) Green:     Host RTS --> Wi-Fi CTS.
• (#5) Orange:   Host CTS <-- Wi-Fi RTS.
• (#6) White:     Host +5V --> Wi-Fi RI/+5Vin.
• Presently Wi-Fi is also receiving +5V via USB from PC.  Ultimately, need to supply +5V directly from Samad's power distribution board.
•       Purple:     WiFi CB1 pin 3 (3VOUT) --> WiFi J10 pin 2 (MAX3237E /EN)
• Presently this is hot-wired directly on the Wi-Fi board to disable input through the level-shifter from the RS-232 port (disable this when not debugging).  When debugging, move the source end of this jumper wire to J10 pin 1 (GND), when host is not powered up.

Now, let's take another look at the wires I'm currently using on GPIO1:

• GPIO1 pin 11 - Host +5V out --> GPS J5 pin 4 (USB5V in).
• Presently, we are also supplying this node from a PC via USB.  Eventually, we need to supply it from Samad's board.
• GPIO1 pin 12 - Host GND out --> GPS J5 pin 23 (GND in).
• Presently, we are also supplying this node from a PC via USB.  Eventually, we need to supply it from Samad's board.
• GPIO1 pin 27 (gpio1_d[20]) - Host PPS_edge <-- GPS J4 pin 15.
• GPIO1 pin 29 - Host +3.3V out --> Vcc in (on Sparkfun level-shifter)
• GPIO1 pin 30 - Host GND out --> GND in (on Sparkfun level-shifter)
• GPIO1 pin 39 (gpio1_d[30]) - Host Rx <-- GPS Tx (on Sparkfun level-shifter)
• GPIO1 pin 40 (gpio1_d[31]) - Host Tx --> GPS Rx (on Sparkfun level-shifter)

We could potentially tie the +3.3V levels on the GPS, the SparkFun level-shifter, the DE3 board, and the OCXO board together, using extra header pins on the GPS, as a way to help make sure the signal levels are all compatible.  Let's use Brown wires for those connections:

• SparkFun level-shifter VCC pin <-- GPS J12 pin 1 (3V3)
• GPS J4 pin 1 (3V3) <--> GPIO1 pin 29 (+3.3V)

And ditto for GND (black):

• SparkFun level-shifter GND pin <-- GPS J4 pin 2 (GND)
• GPS J4 pin 19 (GND) <--> GPIO1 pin 30 (GND)
• GPS J5 pin 24 (GND) <--> GPIO1 pin 12 (GND)

And we can tie the +5V nodes together (white):

• GPS J5 pin 4 (USB5V) <--> GPIO1 pin 11 (+5V)

One problem with making these power connections, however, is that the GPS kit can kinda-power the the DE3 board backwards along the connections.  I'm not really sure if this is a problem or not...  Once all the boards get powered-up simultaneously, it shouldn't matter...

Had an issue where GPIO1 pin 31 (which I tried using as the new host Rx pin for input from GPS) was stuck low for some reason.  I think I vaguely remember running into this issue before.  Now using pin 24 instead (and 25 for Tx output to GPS).

OK, the CTU's serial ports are up and running again with the new cables, but now there's an issue where the GPS module forgot what day it was (I unplugged all its power and the batteries weren't in), so now it's "confused" again.  At least this gave me the chance to exercise a little more of the GPS initialization code.  Fixed a bug that was preventing the time from getting initialized.  It's still not acquiring satellites though...  Part of this might just be due to the heavy rain / thunderstorms happening outside, which may be interfering with the GPS signal.  Not much I can do about that today...  Probably a good time to go home...