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I'd add a pulldown resitor beteween gate-gnd to prevent the gate charging to the threshold voltage and neginning to operate in the linear region during low period of PWM (the threshold voltage is very low only Vsink + 1.4v-2.7v on that FET) although the driver probably has this functionality...
can you clarify what you mean by " "x" bit"? If you mean checking whether a specific bit of a byte size register is some state "x" (1 or 0 ) simply use
if (reg_name[n] = x)
or to check if any bits in the byte are some state "x"
if ((reg_name[7] = x) | (reg_name[6] = x) ....etc)
There's...
Hi Goldsmith,
What do you mean about gate dissipations?
I think the biggest source of power loss will be in the linear region as the gate voltage rises from the gate threshold (~4v) to 10v, so the rise time over this area should be very short- Isn't it best to have as high driving current as...
In order to calculate the gate current for driving the gate of a MOSFET by PWM at ~40Khz, I use the formula for peak current "Ip" located on the 4th page of the publication "http://www.ti.com/lit/an/slua054/slua054.pdf"
My question is what is a systematic way of calculating Ton term in that...
Although I use Altera software, modules will not be visible in the RTL viewer if they do not synthesise properly, so in this case I'd suggest there is an issue with your code. Check warnings to see if inputs to 'Polyphase' drive logic or not. Better yet, simulate the modules together.
A couple of things which may solve the problem you describe:
1. You need to place resistance in series with the mosfet gates for current limiting - use ~22ohm
2. Place a ~2.2k resistor from the mosfet gate to ground.
- - - Updated - - -
Also noticed you have the polarities "+" and "-" for the...
The code wasn't actually mine- just copied straight out of an altera technical publication as an example of what I was trying to do (though the formatting didn't copy across). - but I tried assigning all the reg values I was using to wires to connect to the ports of the divider module being...
As you suggested, it looks like instantiating the block explicitly inside the verilog module is the way to go. I'm just having a problem now getting the division to simulate correctly (it only synthesises to a few percent of what a 32 bit divider should, so the divider isnt being synthesised for...
Yes, this is very simple to achieve. The parallel port being controlled by mach 3 uses 2 pins to control each motor- 1 pin sends step pulses, and 1 pin is high or low to give direction (more optional pins such as an enabling pin may also be used) A complete CNC, simply uses 2 pins per axis this...
In one of my designs I use a block symbol which I created from a verilog module- It has an output which gets passed through a divider block (from the megafunctions library) and the result is fed back into the module. How can I make these into a single block for the sake of simplicity?
You're correct- I wasn't thinking enough when I wrote that. the D term should be kd*the difference between 2 successive errors over the sampling period.
as for
(ki*(integral +distance error*dt))
If you mean integral as in (sum of previous errors * sampling time) rather than the whole...
Yes- the PID code is easy to implement on something like a PIC- its a very simple algorithm.
Effectively you will be writing something like:
output = kp*(distance error) + (ki*(distance error + previous distance error)) + kd*(distance error/sampling time)
You will need to scale and filter...
Do you mean you are having a problem designing the electronics to drive the motor, or the function that would control the motor? If I understand what you're trying to do, for something like 'cruise control' you could use your typical PID algorithm using distance measured by the ultrasonic sensor...
what method are you using to 'draw' the block diagram? Are you using "file > create/update > create symbol files for current files" after compiling the above VHDL code? This should automatically give enough connections for all ports listed in the VHDL. Or are you saying you're trying to 'draw' a...
Not familiar with the board- but if it has an existing USB port, does it also have a dedicated UART chip? I have made an FPGA based board controlled through Matlab using a USB -> UART chip, which seems to be a lot less effort than making a completely FPGA based USB interface (manufacturer...
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