i can't seem to get this working and ive tried i think every possable way to get it to work. btw i bought it at http://www.robotshop.us/inex-serial-real-time-clock.html it has some PDF files on the board. if someone can tell me how to correction wire and interface it with an arduino that would be very helpfull. ive searched google and read teh manuel many times and still can't get it to work.
Not sure if I can help on this, but after reading the data sheet, I have these observations:
Serial TTL on the Arduino is full duplex with a TXData line and an RXData line. Interface for this would be three wires to the microcontroller.
According to their description, this board uses Serial TTL half-duplex with a single line combining TXData and RXData functions. You send it a command and it spits back data on the same wire. Interface for this would be two wires to the microcontroller.
Some serial servos are half-duplex, here's how Trossen Robotics handles it http://forums.trossenrobotics.com/tutorials/how-to-diy-128/controlling-ax-12-servos-3275/
The Arduino presents slightly more of a challenge. The AX-12 servo has 3 lines on the bus: Power, Ground, and Signal. How does it use only one signal? Only one device on the bus can talk at a time. This is known as half-duplex serial. This poses a challenge on our AVR, since the hardware serial UART has separate lines for the RX and TX. We have two possible solutions:
- Add additional circuitry to convert full duplex to half duplex, or
- Tie the RX and TX lines together, and be safe about our code. This is the route I will take.We need to be sure that any time we are recieving, we turn off our TX channel.
Maybe this can spark some ideas for you or someone else replying...
Here's a description of using a diode to block the TXDATA line from interfering with the RXData line when you combine the two for half-duplex...
I remember doing this on RS232 back in the day for some weird interface from a device to a computer...