AM2634: EQEP - position counter latch using strobe signal triggered by SOCA

Jan J

Part Number: AM2634
Other Parts Discussed in Thread: SYSCONFIG

Hi all,

I am working on the EQEP unit and trying to latch the position counter using the strobe signal triggered by SOCA, which is generated using EPWM0. To do so I configured the example.syscfg as follows:

Strobe Event Latch (SEL): On rising edge of strobe

Strobe Source: Strobe signal is OR'd with ADCSOCA

QEPA Source: Signal comes from Device Pin

QEPB Source: Signal comes from Device Pin

Unfortunately the position counter does not get latched. The EQEP_QEPSTROBESEL register (64h) seems to be configured correctly (STROBESEL[1-0] = 0x2). In the EQEP_QEPSRCSEL register (6Ch) the QEPSSEL bits (28-24) are defined as 0x0.

-Am I missing something? What configurations need to be done to latch the position counter using the strobe signal triggered by SOCA?

Thanks!

Best regards,

Jan

over 2 years ago

0 Frank Livingston over 2 years ago

TI__Mastermind 29388 points

Hi Jan,

I'm looking into this and will get back with you shortly.

Regards,
Frank

0 Frank Livingston over 2 years ago

TI__Mastermind 29388 points

Hi Jan,

Sorry for the delayed response. I'm still working on this and expect to have an answer by tomorrow.

Regards,
Frank

+1 Frank Livingston over 2 years ago

TI__Mastermind 29388 points

Hi Jan,

There is a HW bug on AM263x where the EPWM SOCA/B inputs to EQEP are connected to 0.

There are also bugs in the:

AM263x TRM (https://www.ti.com/lit/pdf/spruj17): feature should be listed as not supported
AM263x Registers Addendum (https://www.ti.com/lit/pdf/spruj42): EQEP_QEPSTROBESEL register should mention feature is not supported
MCU+SDK: Sysconfig shouldn't allow configuration of stobe signal as being OR'd with ADCSOCA or ADCSOCB.

The current solutions for this issue is to route the signals at the device pin level:

route SOCA/B to OUTPUTXBAR, connect to GPIO
route GPIO via INPUTXBAR & PWMXBAR to STROBE of EQEP.

The application will need to account for the delay on this path and also the board.

EQEP strobe select options are shown in the TRM, Figure 7-211. EQEP Integration Diagram. These include the Device Pin and the PWM XBAR outputs 29:0.

The strobe signal mux is configured using EQEP_QEPSRCSEL:QEPSSEL [28:24]. There is an SDK function EQEP_selectSource() for configuring the EQEP_QEPSRCSEL register.

Regards,
Frank

0 Jan J over 2 years ago in reply to Frank Livingston

Prodigy 145 points

Hi Frank,

thank you very much for your assistance. Will this HW bug get fixed in future versions or will this feature not be available for the AM26?

Best regards,

Jan

0 Frank Livingston over 2 years ago in reply to Jan J

TI__Mastermind 29388 points

Hi Jan,

Yes, it will be fixed.

Regards,
Frank

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AM2634: EQEP - position counter latch using strobe signal triggered by SOCA