LAUNCHXL-F280049C: Configuration difference between GPIO18 and other GPIOs

Green Deng

Part Number: LAUNCHXL-F280049C
Other Parts Discussed in Thread: SYSCONFIG

Dear team:

There are instructions on the datasheet:

General-Purpose Input Output 18. This pin and its digital mux options can only be used when the system is clocked by INTOSC and X1 has an external pulldown resistor (recommended 1 kΩ).

My customer want to configure GPIO18 as PWM6A output. He made the following modifications:

In Initsysctrl(), he change InitSysPll(XTAL_OSC,IMULT_10,FMULT_0,PLLCLK_BY_1); to InitSysPll(INT_OSC2,IMULT_10,FMULT_0,PLLCLK_BY_1);

And set GPyGMUXn.GPIOz and GPyMUXn.GPIOz register bits of GPIO18 to 5 (i.e. EPWM6 function),

After that, configure EPWM6 accordingly.

However, after completing the above configuration, the output of GPIO18 is always low, and other pins can work normally.

Is there anything else that needs to be configured?

Best regards

over 4 years ago

+1 Leon Linder over 4 years ago

Intellectual 450 points

Hello,

if I understood correctly, both the GPyGMUXn.GPIOz and the GPyMUXn.GPIOz were set to 5. Correct would be:
GPyGMUXn.GPIOz = 1
GPyMUXn.GPIOz = 1
For comparison in SPRUI33D page 869 table 8-6 to set.

If this was set correctly, it is possible that the direction was not defined correctly. In GPADIR.bit.GPIO18 should be a 1, so that it is defined as output.

Best regards
Leon