You probably should be able to control the SSC-32 using TTL with most any controller. I do not know anything about your controller. A quick look up on the web gives me the impression that it runs on 3.3v. I did not look to see if the IO pins on this board can directly handle 5.0v or not. So you may need some circuitry to handle voltage differences.
For any of us to help you, we would need additional information. Things like:
How are the two boards connected to each other. For BiDirectional communication between the SSC-32 and another board you will need at least three wires connecting them. One that you output on on your controller that goes to the RX input of the SSC, a ground wire between the two boards and then a wire from the TX output of the SSC to an input line on your controller board.
Have you set the BAUD rate on the SSC-32 board to the same speed as what you are trying to read or write on your controller board?
If you are trying to do TTL type communication on your board and the other board sends you something and your program is not waiting in a read statement (whatever form that is on your board). Is the input automatically buffered somewhere or is it lost.
My JSTIK board likes 3.3v TTL signal levels. IT will work with 5V TTL stuff and 3V CMOS. Does not like 5V CMOS.
I’ve configured my JSTIK software to 115.2K baud 8-N-1, and I removed all baud jumpers to get the SSC-32 to 115.2K baud as well.
I was able to get signals to the SSC-32 just fine. I can send commands to it with out a hitch via the TTL connections and control my two test servos.
In a test, I verified that my JSTIK is able to receive what it sends by tying its input TTL to its output TTL thus creating a loopback.
I found the ground plane on my interface card (a JSimm Card) and I’ve connected that to the ground pin on the SSC.
I just upgraded the firmware last night and I’m going to try to receive data from the SSC via TTL this AM. Hopefully the combination of the ground plane connector and new firmware will allow me to receive data in addition to sending it.
If there’s anything else you can suggest, I’m all ears!
Connect your ssc-32 to a computer and verify it is working correctly. If it is then your issue is with the controller your are connecting to it. After sending a command, is your controller waiting an appropriate amount of time for data to be generated and returned from the ssc-32?
Downloaded LynxTerm software, connected via RS232 at 115.2K 8,N,1 tried out the UI - NICE!. Updated the firmware to 2.02GP. Was able to send any and all commands and get back all responses.
I wired up the TTL pins as per the instruction manual including connecting the ground pin. I was able to send commands to the SSC but not receive them. I verified that my wiring was correct and that the JSTIK was able to send and receive serial data via its TTL pins (i placed a jumper between TXD and RXD and ran my SSC program. I saw the commands that I would have sent to the SSC)
Ok. So here’s what I know.
I’ve got an SSC-32 v2.02GP
The SSC works with the RS232 levels from a PC.
The SSC works with the RS232 levels from a JSTIK
The SSC receives with the TTL levels from a JSTIK
The JSTIK does not receive TTL from the SSC **
THe SSC does not send TTL to the JSTIK **
** I cannot verify if the SSC sends TTL properly.
Analysis with a Digital Multimeter on the RX line of the SSC shows it sitting at 1.25V. The TX line sits at 4.97v. By sit, I mean while the board is idle and freshly booted.
I’m not sure what the voltage would be if TX were being driven low. I suspect that it’s low is not low enough to meet the threshold of my JSTIK.
What voltages indicate low/high on the TX Line? If they’re outside the range of the JSTIK I’ll have to build some sort of circuit to adjust the voltage range before it gets to my TTL RXD input on the JSTIK.
If you can communicate with the ssc-32 from a computer, then the ssc-32 is probably doing proper TTL communication. The ST202EC chip on the ssc-32 board is converting/inverting the board TTL to RS232 for communication with a computer.
Looking at the “TTL Serial com. SSC-32 side…” in the “Shorting Bar Jumpers and Connectors at a glance” section in the ssc-32 users manual, there is no connection in that configuration to the ssc-32 output. The Tx on the ssc-32 is not connected to anything, so if you are wired this way, it might be a problem.
The online version of the SSC-32 manual now shows a proper configuration for bidirectional communications with another board. I have used this on my CHR-3 hex to enter the “Q” command to find out if the SSC-32 has finished processing the last command or not. Also for awhile others have used this on their phoenix. Not sure if they still are, or are now using timing information to know when to enter a new command.
This pin goes directly to pin 3 of the Atmega chip.
Yes I would expect the TX line to set at about 5v. I also would expect that it would pull it down to near zero when low. As for low enough, not sure, there are others better with the electrical stuff. I know on a propeller chip (again 3.xV) I have used resistors inline to connect some 5v devices to it…
