A brief introduction to the STM8 RC touch library

The touch detects that a key is pressed and the calling process is: TSL_Action -> TSL_SCKEY_P1_Acquisition() -> TSL_IO_Acquisition() -> TSL_SCKey_Process() -> TSL_SCKey_DetectedTreatment(), where TSL_Action() and TSL_SCKey_Process() have other state changes and processing.

The TSL_IO_Acquisition() function is a charge and discharge time detection function. The most important variables should be the charge and discharge time and the number of times it is detected that the value exceeds the preset range. They will be used outside the function, namely FinalMeasurementValue and RejectionCounter.

void TSL_IO_SW_Burst_Wait_Vil(void)//Only view the contents of IAR compiler

{

#if defined(_COSMIC_)

......

#elif defined(_IAR_)

  __asm("ld a, S:AcquisitionBitMask"); //Put AcquisitionBitMask into a

  __asm("ldw x, S:sTouchIO"); // Put sTouchIO into x Load word (16 bits)

  __asm("incw x"); //Add a word

  // Loop = 1 + 1 + 2 + 2 + 2 cycles = 8 cycles

  __asm("WaitForVil:");

// To be sure that the loop last 8 cycles the first instruction must be a 1-byte instruction

// This is to be sure it is fully fetched in 1 cycle. The second instruction must be shorter than 4 bytes.

// If this not the case, the code must be aligned. 

  __asm("bcp a, (x)"); // 1 cycles logical comparison

  __asm("jreq ??EndWaitForVil"); //Jump to EndWaitForVil

  __asm("ldw y, TIMACQ_CNTR"); // 2 cycles; hw counter also used for timeout ...

  __asm("cpw y, #0x0E00"); // 2 cycles; Timeout compare word value comparison

  __asm("jrult ??WaitForVil");

  __asm("EndWaitForVil:");

#else //_RAISONANCE_

......

#endif

}

The general meaning of this function is to detect the level of the corresponding pin until the same level or timeout jumps out. The value of the TIMACQ_CNTR counter should be loaded in FinalMeasurementValue (I don’t know if it is correct, please correct me)