I was wondering on what frequency you should drive the motors from the formula chassis. I only use the chassis, so I need to know what the ideal frequency should be.
I'm now driving them on a frequency of 76 Hz. This is the lowest I could get with the external cristal.
Now the problem is that I don't have any power on my wheels
If I touch the wheels really light, they already stop moving
Sounds like a power problem rather then a frequency problem as when we are driving the motors at 100% there is no frequency present, just DC +5V.
Are you driving the motors off a boosted motor controller chip or straight from an I/O pin. We use a L293D IC to amplify the current from the PICs PWM outputs. This also allows us to control the direction of each of the motors by using another output I/O per motor to act as the source or drain to each individual PWM channel.
That is maybe the problem, but I have the motors driver board EB0022-00-2.
Can I use this one to solve the problem? Can you tell me how I have to connect it then? I'm not really getting it.
How do I have to set jumpers and stuff?
I have already tried to connect straight from the chassis with the batteries voltage (6V) on VPwr. I powered the board on V+ from the microcontroller board. But then there was a short circuit somewhere.
Thanks in advance
The EB-022 can be configured in a number of ways. The simplest configuration has a bank of jumpers across J1 (DEFAULT) and two jumpers on J13 connecting each middle pin to the pin above (with the board orientated so that the two D-type connectors are on the left-hand side and the power supply input terminals are at the top).
In this configuration both output channels are permanently enabled and the 4 motor outputs (2 for each motor) are directly controlled by port pins 0 to 3 (pins 1 to 4 of the lower D-type connector).
If the jumpers on J13 are moved to connect the two middle pins to the two lower pins, the enable signals for each channel can be controlled by port pins 4 and 5.
If the jumpers on J1 are moved across to J10, all the inputs are routed through the PATCH system (J11,12). This allows free allocation of the port pins so that PWM signals can be routed to the appropriate controller inputs.
J11 connections, reading from the top, are D-type pins 1 to 8 in sequence.
Each motor can be individually controlled by connecting a PWM signal to the EN input (speed) and forward and reverse controls to the two IN inputs.
Alternatively, to save I/O, the motor can be permanently enabled (J13 connected centre to top), PWM applied to one of the IN inputs and a direction signal applied to the other IN input.
In this configuration the direction input opposes the PWM input.
Example:
When the direction input is low, the motor is driven forward with speed control = PWM
When the direction input is high, the motor is driven in reverse with speed control = 100% - PWM
The EB022 board must have supply voltages connected to a +V terminal (+5v) and the VPWR terminal (motor voltage). A GND terminal must also be connected to an external power supply if one is being used.
