How to change CCG3PA project to have no feedback implementation?

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JoLu_3455101
Level 4
Level 4
5 likes given 5 solutions authored 25 replies posted

Hi,

The default CCP3PA project (CY4532 EVK with CYPD3171 CLA implementation) uses direct feedback implementation. In the firmware, there's the following defines in config.h:

VBUS_CTRL_NONE                              (0)

VBUS_CTRL_PWM                                (1)

VBUS_CTRL_DIR_FB                            (2)

VBUS_CTRL_OPTO_FB                           (3)

VBUS_CTRL_TYPE_P1                           (VBUS_CTRL_DIR_FB)

My hardware doesn't use the CYPD3171's Feedback pin. I am using a GPIO to toggle between 2 voltage options (5V or 9V) from my external regulator. When I use VBUS_CTRL_NONE, my application doesn't work (or run) at all because it seems VBUS_CTRL_NONE is not really implemented. If I use VBUS_CTRL_DIR_FB, my 5V (default) option works, but with all the idac calculations in vbus_ctrl.c (which I think isn't necessary for my implementation), I cannot get my 9V option to work even after setting my GPIO pin. Hardware-wise, the GPIO pin did set, but my PD analyzer keep showing "hard reset" after a successful 9V negotiation over CC pin. Maybe I am missing something in the firmware. I tried commenting out some of the idac calculations code, but that didn't work.

Is it possible to implement a no feedback option?

Thanks,

Jonathan

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1 Solution

Hi Lisa,

Thanks for your reply. I've did some digging and it appears that there was a timer in the feedback code that I needed for my no-feedback implementation. I have added it to my own function and it is working now.

I have a separate question related to the CY4532 EVK, but I will create a new topic on this.

Thanks,

Jonathan

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