DEVKIT-MOTORGD Schematic

[jjacp]

Hello,

Does anyone know where I can find the schematic for the motor shield (DEVKIT-MOTORGD) used with the MPC5744P Dev Kit? The only document that I can find is the Quick Start Guide.

Thanks!

[darrin_weiss]

FYI, schematics are now available under the "TOOLS & SOFTWARE" tab for MOTOR-GD.

Low-Cost Motor Control Solution for DEVKIT Platform|NXP 

[Daniel_Popa · Accepted solution]

Hi jjacp‌,

You are not the first one asking about this. Another topic is here: DCBV and Phase currents range measured_DEVKIT-MOTORGD? 

Unfortunately, nothing has been changed so far - so please use the same advice i gave there:

please provide schematics for your MOTORGD, if you do not have the updated version, the old version is fine to me.

Unfortunately, i do not have the clearance to do that. Please contact your sales representative and ask him/her for this information. The document exists but currently is just for NXP internal use only.

If you need specific information about specific parts of the schematics let me know and i'll try to explain that functionality.

Thank you!

Daniel

[jjacp]

Hi Daniel,

I tried changing the DC_BI offset in the model from 2048 to 1024, and the reading is much more reasonable now:

Thanks!

[Daniel_Popa]

Hi jjacp‌,

That is not enough. The BLDC Workshop was designed for beginners and i tried to add some features inside just for awareness - but is did not had time to discuss all of them in details since that was not in the scope of the lecture. One of these features is how to measure the currents - especially the ones that varies depending on the PWM.

Since you seems to be a more advanced user - i think you should be able to manage the correct way of implemented the current measurements (i'll touch that in lecture of PMSM Workshop later on)

So, here is what you need to know in respect with Vdc Current and Voltage HW circuit schematics:

As a hint, please check Motor Control Class: Lecture 4 - BLDC Motor Theory 

A correct DC current implementation should take into consideration 3 things:

- Commutation method (2 out of 3)

- PWM strategy

- Motor Speed, basically the PWM duty factor

For example this pictures shows commutation sequence in ideal conditions (100% duty cycle). In normal circumstances the currents will not look like that - therefore affecting the measurements.

Hope it helps - and i look forward to see your implementation

Best regards,
Daniel

[jjacp]

Thank you dumitru-daniel.popa for the hints and information! I'll try to figure it out.

[jjacp]

Hi dumitru-daniel.popa‌,

Thanks for the info! Hopefully sales or the design team releases the schematic one day. 

And thanks for the link. My question had to do with the ADC as well. I'm on Lecture 12 of your BLDC class, and it's working on my setup, but the DC_BI current measurement seems way off (see screenshot below). I was thinking maybe it was because the calculation in the model was off because I'm using a different motor than the Linix one, hence why I wanted to see the schematic.

From the thread link you sent, I verified that J9, J10, and J11 are set to 2-3 for BLDC, and J8 is open. 

Thanks!