cameraftdiserial
I bought this serial electronic brick camera from Robot shop recently. I connected it to a Spark Fun FT232R shield. I am able to open my virtual COM port but I am not able to capture any images.
This is what I did on the spark fun shield's end:
Can anyone throw some light where am I going wrong?
Beware that there are several versions of USB / SERIAL adapters. The standard type, and the kind you want for connection to your server's D-Sub 9 connector, will be one that comes already with its own D-Sub 9 connector. These have an internal FTDI chip that converts from USB to a serial logic level signal and then an RS232 transceiver part that converts the logic level serial over to the +/- bipolar signalling used by the standard serial port.
You will most likely need a null modem adapter between the USB/SERIAL adapter and the server computer serial port connector. A really convenient type of null modem adapter for this use looks like this:
The other type of FTDI USB to serial adapter is one that does not include the RS232 transceiver chip. These bring out the logic level serial lines so that they can be connected directly to a microcontroller or other circuit. It alleviates the need to put standard RS232 transceivers for a debug port or programming port on MCU hardware to save space and cost whilst at the same time when the usage model is for very short cabling lengths. One example of this type of FTDI adapter looks like this:
Note that is not possible to try to use a logic level serial adapter to "talk" to the standard RS232 port off your server. The voltage levels do not match and the logic level signals are logically inverted from standard RS232 signals. (i.e. the RS232 transceiver parts have a logical inversion through the part).
Well I'd start with the datasheet for the ralink. He's clearly the controller in this system. You could look at its pin list, find the location of serial or jtag pins, and then search that corner of the chip on the board. It will take a lot of poking and measuring but maybe you'll get lucky and their boot loader puts a message out at startup and you can see that on a scope.
Reverse engineering is an exercise in patience and trial and error, followed by more trial and error.
On the other hand the Linux files are not stored in the ralink but rather externally in a little flash part. The datasheet suggests it supports boot from spi-flash, so look up the other part numbers on the chips on your board and see if one is a spi-flash. You could then just pull it off and program it with a little programmer (they're not that expensive). That might be an easier path if you know what needs to be programmed in. Even better if you have another camera and you could just clone its flash.
It does mention nand flash support but I didn't see boot from nand flash.
Best Answer
Depending on the device the manufacture will sometimes label RX and TX from either the DCE or DTE perspective. You need to make sure the transmit line of your one device is tied to the receive line of your second device and vice versa. Try crossing over your RX and TX with a null modem adapter and see if that helps. If you tied the transmit line of one device to the transmit line of the second the communication will not work.