you are correct in (almost) everything you have described.
Almost? What did I get wrong?
We realised that PL2 wasn't activated, to which SGX responded, that they can provide the C source files so that customers can update the firmware themselves. But since our IR-EK2 board recently broke (short-circuited probably, can't figure out exact problem), we ordered a new one and asked SGX to update the firmware with PL2 enabled. Awaiting a response now on whether they will do it or not.
It would be best if the board could just receive commands through either the USB serial or the PL2 serial. Alternatively they should have made a jumper bridge you could take off and connect your own serial 3.3 V interface in stead of the CP2102.
We actually cut the tracks for P38 and P39, used a level converter and still couldn't establish a connection over a serial com. port. P38 and P39 transfer data via UART, so UART to UART communication should be possible over RS-232. We have another serial port which we will test out once the new board arrives. Maybe there was something wrong with our other port.
That is not good that the board broke that way. However check these 4 points:
1. In serial communication there is sometimes a confusion between what is Tx and Rx. Sometimes you use cross connection (Port-A Tx to Port-B Rx, which makes sense to me), but other times you connect Port-A Tx to Port-B Tx.
2. Did you remember to connect GND from your serial port to SGX GND?
3. RS-232 to UART? RS232 has reversed levels as TTL serial
. What is RS232 -10V is TTL +5V; RS232 +10V is TTL 0V. If you just scale with resistors you would have to put it through a NOT gate (e.g. 7404 chip) to have correct levels. Better use a converter chip like Max232.
4. What is the UART speed? 9600 BPS or something else? Did you set it right?
We were also thinking of using an ARM computer, Arduino, to establish wireless communication. If time permits, we will go down this path. Otherwise someone else would have to look into this and see whether they can build a board specifically for our sensor, with corresponding program logging all data on a PC.
We can talk about that later, if you still have a problem.
It cannot take measurements from a distance and due to the evaluation board's size it is attached to the underside of the quadcopter. This will of course affect measurements and they cannot be taken by their absolute value, but you can still get a relative idea of how an areas' air quality is. Especially collecting data in places that are hard to reach with conventional methods.
5-10 m below my octo-copter there is strong wind movement. Probably best placement would be 50-100 cm ahead of front rigger, with batteries placed to counter balance at the back rigger.
I will write another entry once we figure out how to make the board communicate (with or without Wi232).
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am 14.08.2015 19:53. »