Rotary potentiometer code

[spiovan9]

Posted on October 10, 2011 at 21:47

Hi all,

some piece of code to manage a rotary encoder potentiometer. The model I use is from the chinese market maybe by TREXON. I'll propose both interrupt and polling mode. The interrupt code has been adapted from http://www.arduino.cc/playground/Main/RotaryEncoders and the polling one from http://stackoverflow.com/questions/34735/using-a-rotary-encoder-with-avr-micro-controller. Find also the interrupt handler (just modify the stm8s_it.c code as indicated). The code is a part of a hobby project which is a PLL 2.4GHz signal reference generator. The rotary potentiometer if for making a ''knob'' for such a generator to move the output frequency of the PLL. The project also has a 12 keys keypad and a LCD 16x2 display, which I have already posted. The rotary potentiometer CHA goes into GPIOB.PIN0 and the CHB into the GPIOB.PIN1. Hope it helps. Stefano ________________________ main() { .. .. while(1)     {          &sharpifdef _POLLMODE_         wheel = (GPIO_ReadInputData(GPIOB) & 0x03);         if(dir == 0)         {             if(wheel == 0x01)                 dir = 2;             else if (wheel == 0x02)                 dir = 4;             else                 dir = 0;         }         else if (dir == 2)         {             if (wheel == 0x01)                 dir = 2;             else if (wheel == 0x00)             {                 // decrease frequency                 VCOFreq -=100;                 PLL_SetFreq(VCOFreq);                 LCD_Cmd(LINE_2);                 Int2Str(sz_Val, VCOFreq);                 pos = 7;                 LCD_Str(sz_Val);                 dir = 0;             }             else                 dir = 0;         }         else if (dir == 4)         {             if (wheel == 0x02)                 dir = 4;             else if (wheel == 0x00)             {                 // increase frequency                 VCOFreq +=100;                 PLL_SetFreq(VCOFreq);                 LCD_Cmd(LINE_2);                 Int2Str(sz_Val, VCOFreq);                 pos = 7;                 LCD_Str(sz_Val);                 dir = 0;             }             else                 dir = 0;         }         else if (wheel == 0x03)         {             dir = 0;         } &sharpelse // INT MODE     if (changed)         {             BEEP_Cmd(ENABLE);             VCOFreq = counter;             PLL_SetFreq(VCOFreq);             LCD_Cmd(LINE_2);             Int2Str(sz_Val, VCOFreq);             pos = 7; // force cursor position <> 0 to simulate typing a new value from the keyboard             LCD_Str(sz_Val);             changed = 0;             BEEP_Cmd(DISABLE);         } &sharpendif ____________________ /**   * @brief External Interrupt PORTB Interruption routine.   * @par Parameters:   * None   * @retval   * None */ &sharpifdef _COSMIC_ @far @interrupt void EXTI_PORTB_IRQHandler(void) &sharpelse /* _RAISONANCE_ */ void EXTI_PORTB_IRQHandler(void) interrupt 4 &sharpendif /* _COSMIC_ */ {         u8 portval;          portval = (GPIO_ReadInputData(GPIOB) & 0x03);     if ((portval == 0x03) || (portval == 0x00))     {         counter-=200;     }     else     {         counter+=200;     }     changed = 1; // this is to tell the main to display the new value      } #interrupt #encoder