interface question
interface question
by Miamicanes
Fri May 25, 2007 7:04 pm
I'm building a board to let my new SunSPOT controller communicate directly with the Dynamixels. I just want to verify that my assumptions are right:
1. Pin 1 carries 9.6v, used by the motors
2. Pin 2 is ground. Pin 2 should also be connected to the Sunspot's ground to ensure that the SunSPOT and circuit boards on the Dynamixels both have the same opinion as to what constitutes 'ground'. (The SunSPOT itself runs on 3v and has its own battery; it also makes +5v available, which I'm using to power a TI 74LVC1T45 level shifter sitting between pin 3 of the 5v Bioliod communication bus and the 74hc126 & 74hc04 running at 3v connected to the 3v SunSPOT.)
3. Pin 3 is communication. It uses 5v logic. It's half-duplex and requires a 74xx126 and 74xx04 to connect the pin to the proper port.
Also, is the baudrate autodetected, or MUST you connect to the Dynamixels first at 1mbps in order to change the rate to something slower, like 512kbps, 256kbps, or 128kbps? If the baudrate gets changed, is the change persistent, or do you have to reconnect at 1mbps the next time the power is cycled to slow it down again?
Finally, is the +9.6v from the cm5 always powered up when the cm5 is turned on, or does a command need to be sent to the cm5 to explicitly turn on the power? In other words, if I'm just using the CM5 as a rechargable battery, do I need to do anything besides simply turn it on?
1. Pin 1 carries 9.6v, used by the motors
2. Pin 2 is ground. Pin 2 should also be connected to the Sunspot's ground to ensure that the SunSPOT and circuit boards on the Dynamixels both have the same opinion as to what constitutes 'ground'. (The SunSPOT itself runs on 3v and has its own battery; it also makes +5v available, which I'm using to power a TI 74LVC1T45 level shifter sitting between pin 3 of the 5v Bioliod communication bus and the 74hc126 & 74hc04 running at 3v connected to the 3v SunSPOT.)
3. Pin 3 is communication. It uses 5v logic. It's half-duplex and requires a 74xx126 and 74xx04 to connect the pin to the proper port.
Also, is the baudrate autodetected, or MUST you connect to the Dynamixels first at 1mbps in order to change the rate to something slower, like 512kbps, 256kbps, or 128kbps? If the baudrate gets changed, is the change persistent, or do you have to reconnect at 1mbps the next time the power is cycled to slow it down again?
Finally, is the +9.6v from the cm5 always powered up when the cm5 is turned on, or does a command need to be sent to the cm5 to explicitly turn on the power? In other words, if I'm just using the CM5 as a rechargable battery, do I need to do anything besides simply turn it on?
by billyzelsnack
Fri May 25, 2007 7:51 pm
I'm pretty sure baudrate is stored in the ROM and it does not auto-detect.
I use the CM-5 as just a battery pack with my interface. It's actually very convienent. My interface plugs right into the CM-5 with just ground and signal and the CM-5 gives the servos power.
I use the CM-5 as just a battery pack with my interface. It's actually very convienent. My interface plugs right into the CM-5 with just ground and signal and the CM-5 gives the servos power.
Re: interface question
by JonHylands
Fri May 25, 2007 10:36 pm
Miamicanes wrote:1. Pin 1 carries 9.6v, used by the motors
2. Pin 2 is ground.
This is backwards.
Below is what you need:
When you're looking at an AX-12 from the connector side, ground is the right pin, power (9.6 volts) is the middle pin, and data is on the left...
- Jon
