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CCS/TMS320F28379S: ISR timing problem with resolver library float call resolver_algo_Float()

sterie
Intellectual 350 points
Part Number: TMS320F28379S


Tool/software: Code Composer Studio

Hello,

we have implemented the resolver interface like in the TI/IDDK_PM_Servo_F2837x example code.

Using a 160kHz ISR for generating the DAC values from the table, reading the sin and cos ADC values. Also calling the library function resolver_algo_Float() and resolver_PostProcess() during the ISR like in the example code.

But if we measure the ISR timing we got a problem. Every 16th ISR duration is longer than the other and needs more than the next 160kHz ISR call would occure. The normal ISR duration is ~1.6µs but every 16th. needs up to 8µs and this is longer than the ISR is called again by 160kHz.

Is there a knowen problem with the functions resolver_algo_Float() or resolver_PostProcess()?

How long should be the duration for the function calls?

Yours, Stefan