TMS570LS1224: Information from N2HET to CPU

Hello Miguel,

For motor control, the MCU needs to generate PWM signals, capture the impulse, and sample the ADC. For PWM, normally 3 instructions are used: counter (CNT), compare(ECMP etc), update (MOV32, MOV64, RADM64 etc). You can update the PWM period and duty cycle by write the data directly to the data field of update instruction (for example MOV32).

The N2HET RAM is implemented as 4 banks of 96-bit wide two port RAM. This means that there a total of 8 ports available; four read and four write. Normally the N2HET will use up to two of these ports at a time. One read port is used to allow the N2HET to prefetch the next N2HET instruction while a write port may be used to update the data or control fields that have changed as a result of executing the current instruction.

N2HET accesses to its own internal RAM are given priority over accesses from an external host (CPU or DMA), this makes N2HET program execution deterministic which is a critical requirement for a timer.

Each N2HET instruction is 96-bits wide but aligned to a 128-bit boundary. Instructions consist of three 32-bit fields: Program, Control, and Data. If the MOV32 is the 3rd instruction of your code, you can access the data field by using:

hetRAM->Instruction[3].Data

HALCoGen generated a example code to get/write value from/to the NHET RAM, for example:

pwmSetSignal(hetRAMBASE_t * hetRAM, uint32 pwm, hetSIGNAL_t signal);

edgeGetCounter(hetRAMBASE_t * hetRAM, uint32 edge);

...etc

You can call those functions in your RTI ISR. 

Hi Wang

Thanks for your reply

QJ Wang said:

For motor control, the MCU needs to generate PWM signals, capture the impulse, and sample the ADC. For PWM, normally 3 instructions are used: counter (CNT), compare(ECMP etc), update (MOV32, MOV64, RADM64 etc). You can update the PWM period and duty cycle by write the data directly to the data field of update instruction (for example MOV32).

Im using the EPWM module for the PWM generation. Im only missing the feedback to do the control. 

If understand you correctly this line

QJ Wang said:

edgeGetCounter(hetRAMBASE_t * hetRAM, uint32 edge);

I could use it to get the edges according to the name I give to each edge based on the RAM they are?  

something like edgeGetCounter(hetRAMBASE_t * 1, uint32 encoder_1_a);?

that way I would directly recover the actual data from encoder 1 channel A? 

Thanks