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Forum Newbie
Group: Forum Members
Last Login: Monday, April 20, 2009 10:20 AM
Posts: 1,
Visits: 3
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We recently purchased the Serializer, and it seems to be working great so far, excellent product!
We'll be using it to drive two motors that will be chewing through a LOT more than 4-amps (something on the order of 20 amps), so we'll be using the Serializer to drive a set of external H-Bridges.
Question: What does the "Enable" line do? As far as I can tell, it's always tied high. When I issue the command "stop" in Hyperterm, the PWM stops, but the Enable line stays high. Additionally, when I issue "pwm 1:0 2:0" the Enable line still stays high.
I'm kinda lost as to when this line ever goes low, and what exactly it does?
Also, when the "stop" command is issued, do the on-board H-bridges brake, or do they free-coast?
Basically, we're trying to figure out how we can take the signal from the Serializer and connect that to a VERY high current H-Bridge.
Or if you know of someplace that sells premade high-current H-Bridges, that would be sweet.
Thanks for your help!
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Supreme Being
Group: Administrators
Last Login: Monday, October 31, 2011 9:18 PM
Posts: 640,
Visits: 819
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That is a very good question regarding the enable line... Acutally, it is used internally by the firmware, but we never added a command to control it for an external h-bridge.  So, we need to do that. In the meantime, if you need to 'enable' your h-bridge, you can simply tie the enable line to one of the 5V pins on the Serializer's headers. If you're using our 10A H-Bridge, the enable line is already tied high by default, so you don't have to 'enable' it. When the stop command is issued, the motors should free coast (if they have enough mass/energy stored up to continue spinning). Best Regards!
Jason Summerour
President,
Summerour Robotics Corporation
www.roboticsconnection.com
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Forum Newbie
Group: Forum Members
Last Login: Saturday, April 25, 2009 8:12 AM
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Hey just the topic I was looking for  . I'm working on getting my Sabertooth 2x25 motor driver and Serializer to work together. I too have larger 24v motors that pull around 20amps each so the onboard drivers of the Serializer will not do it for me. Although, I'd really like to use the PID on the serializer, cause it does a really good job I am by no means an electronics or programming wizard, so here's what I', going to try. I figure I can either try this either with a circuit using op-amps or use another microcontroller. I'd opt for the MCU since I'm having a hard time grasping op-amps and inverting voltages. I tried an atmega168 running at 16mhz. Reading the pwm pins on the serializer seems to be pretty sloppy with the atmega. I'm assuming the Serializer PWM freq. is faster than 16mhz? I'm not really sure. I have some different PIC's also I didn't try yet. My question I guess is what kind of resolution should I be concentrating on if I want accurate PWM readings from the Serializer pins? Will I need to buy some hi-res ADC chips? At what freq. is the Serializer PWM? I'd really appriciate any help I can get meistro
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Supreme Being
Group: Forum Members
Last Login: Friday, April 22, 2011 6:18 PM
Posts: 153,
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To original poster, names help 
I tested my Serializer WL v1.5.2 for an external h-bridge and got
these results.
PWM command L-Dir R-Dir L PWM R PWM
1:50 2:0 H - Yes -
1:0 2:50 - H - Yes
1:-50 2:0 L L Yes -
1:0 2:-50 L L - Yes
1:-50 2:-50 L L Yes Yes
1:50 2:50 H H Yes Yes
1:0 2:0 ( last state ) - -
Enable shows +5v pwm in PWM:+xx direction
+1v to 2v pwm in PWM:-xx direction ( lo=1v hi=2v above zero)
let me know If I can be of further help.
Don Lewis
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Forum Newbie
Group: Forum Members
Last Login: Tuesday, April 27, 2010 9:18 PM
Posts: 6,
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Hey Guys,
I am using the serializer with the sabertooth 2x25 motor controller and getting erratic motor movement. I was doing some research and wanted to know, what is the frequency of the signal sent through GPIO pin 9 of the serializer?
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Supreme Being
Group: Administrators
Last Login: Monday, October 31, 2011 9:18 PM
Posts: 640,
Visits: 819
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| We don't send pwm out GPIO line 9. It's sent out over the h-bridge pins (L_PWM, R_PWM) (see User Guide). You connect these lines to the Sabertooth Analog input pins. You might also have to use the L_DIR, and R_DIR pins to tell the Sabertooth which direction to drive. Best Regards,
Jason Summerour
President,
Summerour Robotics Corporation
www.roboticsconnection.com
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