AM2434: AM243x-LP

Hi Jinlong, which SDK are you using? MCU+SDK? or Motor control SDK?

From Motor control SDK SDFM's example (AM243x Motor Control SDK: Current Sense) I see below in supported features: 

• 3 SDFM channels on single PRU core
• Normal Current (NC) for data read: SINC3 filter with Over-sampling Ratio (OSR) 16 to 256
• Over-current (OC) for comparator: free running SINC3 filter with OSR 16 to 256
• Event generation(ARM interrupt for data read from DMEM, GPIO toggle for high and low thresholds)
• Single level High and Low threshold comparator
• Trigger based normal current sampling
• Continuous normal current sampling
• Double update: Double normal current sampling per EPWM cycle
• SDFM Sync with EPWM
• Fast detect
• PWM Trip generation for overcurrent
• Clock Phase Compensation
• Zero cross comparator

thank you,

Paula

Thank you. Will look.

thanks

what does SDFM sync with EPWM mean? Does it mean that current measurement is performed at the center of PWM high phase or center of PWM low phase?

Which example project can I use to check if sdfm measurement is performed at the center of PWM high phase or at the center of PWM low phase using SDFM?

Thanks. 

Jinlong, l will send this query to a colleague who is more familiar with the SDFM examples in Motor Control SDK. Please allow him some time to come back to you.

thank you,

Paula

Paula, for now. Why I do see PRU ICSS PWM? We are using only EPWM(s). 
Is PRU ICSS PWM necessary of SDFM sync with PWM?

Hi Paula,
I think we need your help on our site. 
On this page, https://software-dl.ti.com/processor-industrial-sw/esd/motor_control_sdk/am243x/latest/docs/api_guide_am243x/SDFM_DESIGN.html.
EPWM frequency was up to 20 KhZ. Is that the upper limit for customers?
Best,
Jinlong

Hi Jinlong, please wait for my colleague to reply here as these are more Motor Control SDK questions (than pure EPWM questions), which I am not familiar with

thank you,

Paula

Hi Jinlong, with respect to your question if PRU ICSS PWM necessary of SDFM sync with PWM or if we could use EPWM. The answer is that you could use EPWM as well, but I think, when possible, it is better to elaborate on top of a working example from our SDKs

thank you,

Paula

Hi Jinlong, 

Jinlong Shen said:

what does SDFM sync with EPWM mean? Does it mean that current measurement is performed at the center of PWM high phase or center of PWM low phase

It means that the current measurement is performed periodically, and the cycle period will be equal to the EPWM frequency. See the mentioned document: software-dl.ti.com/.../SDFM_DESIGN.html, which shows the SDFM sync with EPWM and also the current measurement start point and timings.

Jinlong Shen said:

Which example project can I use to check if sdfm measurement is performed at the center of PWM high phase or at the center of PWM low phase using SDFM

you can use any one normal current trigger based sdfm example from the motor control SDK, except for the continuous mode examples. 

See for more info about sdfm examples: https://software-dl.ti.com/processor-industrial-sw/esd/motor_control_sdk/am243x/09_02_00_11/docs/api_guide_am243x/EXAMPLES_MOTORCONTROL_SDFM.html#autotoc_md104

Measurment start time is configurable, so you can configure the sample trigger time ({EPWM cycle time }/ 2) in sysconfig to measure at the center of either the PWM high phase or the PWM low phase.

BR, 

Achala Ram

Jinlong Shen said:

for now. Why I do see PRU ICSS PWM? We are using only EPWM(s). 
Is PRU ICSS PWM necessary of SDFM sync with PWM?

Hi Jinlong,

PRU ICSS PWM is used for Over current and fast detect trip generation,  For more info: AM243x Motor Control SDK: SDFM Interface Design

and Only EPWM is required for  SDFM sync 

BR,

Achala Ram

Jinlong Shen said:

EPWM frequency was up to 20 KhZ. Is that the upper limit for customers?

No, as mentioned example is tested up to 20KHz, but you can use higher values as well, there is no limitation with the EPWM frequency.

Hi Paula and Achala,
that the upper limit is not 20 KHZ is great for us. 
I am referring to this page: https://software-dl.ti.com/processor-industrial-sw/esd/motor_control_sdk/am243x/latest/docs/api_guide_am243x/SDFM_DESIGN.html
See section: Sync with EPWM and trigger timing

When search for examples with this: grep -r 'enableIep0ResetOnEpwm0_Sync = 1U' ~/ti/motor_control_sdk_am243x_09_02_00_09/
I only find this example: 
ti/motor_control_sdk_am243x_09_02_00_09/examples/pruicss_pwm/pruicss_pwm_dead_band_epwm_sync/am243x-lp/r5fss0-0_freertos/ti-arm-clang/generated/ti_drivers_config.c

Question 1: If I stick to the linked page, must I use IEP for one of the CMP registers for example CMP0?

Question 2: Can one IEP timer be shared with EtherCAT on one core and with motor running on another core?

Question 3: Actually we need to start the measurement Td time before t_middle_of_duty_cycle (because up-down mode, it is middle of PWM cycle). Td is the half time that 4 current samples run through sinc3 filter. How to visualize the time point  Td +t_middle_of_duty_cycle,  with a GPIO pin state?
We need to run FOC loop at or immediately after Td + t_middle_of_pwm_duty_cycle (i.e. middle of PWM cycle because of up-down mode).


It is a lot of questions. Thank you.

Best regards,

Jinlong             

Thank you, Achala. I will test it.