Capture Qei position and send to usb

thanks:

Such a noise is filtered by,
1) R/C (or L/C) filter at the input pins of the QEI unit.
And
2) The integrated digital filter of the LPC17xx QEI unit.
Is it embedded in the IC or Should I do ?
LPC_QEI->FILTER =???(What should i put??)

As of QEI unit of LPC17xx, an ENCLK_Int interrupt occurs at the every transition of the encoder....
I have written below codes to send the data to usb using usbhost lite.
FILE_Open, FILE_Write & FILE_Close belong to USBHostlite part:

void qei_main(){
        //Basic Configuration:
        LPC_SC->PCONP |= (1<<18);
        LPC_SC->PCLKSEL1  |= (0x01);
        //configuration for the pins:
        LPC_PINCON->PINSEL3 |=((1<<8)|(1<<14)|(1<<16));//PH A&B & index
        LPC_QEI->QEICONF =(1<<2);//PhA and PhB function as quadrature encoder inputs.(4x)
        LPC_QEI->QEICON = 0x02;//Control register: Reset position counter on index.(RESPI)
        LPC_QEI->INXCMP = 0x00;//QEI Index Compare register                                                                                                           LPC_QEI->QEILOAD = 0x00;//QEI Timer Reload register
        LPC_QEI->QEICLR = 0xFFFFFFFF;
        LPC_QEI->QEIIEC = 0xFFFFFFFF;
        LPC_QEI->QEIIES = 0x00000020;//enable ENCLK_EN
}
NVIC_EnableIRQ(QEI_IRQn);               /*enable the interrupt*/
NVIC_SetPriority (USB_IRQn, 1);         /*2nd priority--is it correct??*/

void QEI_IRQHandler(void){
        USB_INT32S  fdw;
        fdw = FILE_Open(FILENAME_W, RDWR);
        if (fdw>0) {
                *UserBuffer=LPC_QEI->QEITIME;
                FILE_Write(fdw,UserBuffer,4);
                FILE_Close(fdw);
        }else{
                return;
        }
        LPC_QEI->QEICLR = 0xFFFFFFFF;   // clear all interrupts
}

Is it correct set priority of USB to 0 and QEI to 1??

kind regards

thanks:

Such a noise is filtered by,
1) R/C (or L/C) filter at the input pins of the QEI unit.
And
2) The integrated digital filter of the LPC17xx QEI unit.
Is it embedded in the IC or Should I do ?
LPC_QEI->FILTER =???(What should i put??)

As of QEI unit of LPC17xx, an ENCLK_Int interrupt occurs at the every transition of the encoder....
I have written below codes to send the data to usb using usbhost lite.
FILE_Open, FILE_Write & FILE_Close belong to USBHostlite part:

void qei_main(){
        //Basic Configuration:
        LPC_SC->PCONP |= (1<<18);
        LPC_SC->PCLKSEL1  |= (0x01);
        //configuration for the pins:
        LPC_PINCON->PINSEL3 |=((1<<8)|(1<<14)|(1<<16));//PH A&B & index
        LPC_QEI->QEICONF =(1<<2);//PhA and PhB function as quadrature encoder inputs.(4x)
        LPC_QEI->QEICON = 0x02;//Control register: Reset position counter on index.(RESPI)
        LPC_QEI->INXCMP = 0x00;//QEI Index Compare register                                                                                                           LPC_QEI->QEILOAD = 0x00;//QEI Timer Reload register
        LPC_QEI->QEICLR = 0xFFFFFFFF;
        LPC_QEI->QEIIEC = 0xFFFFFFFF;
        LPC_QEI->QEIIES = 0x00000020;//enable ENCLK_EN
}
NVIC_EnableIRQ(QEI_IRQn);               /*enable the interrupt*/
NVIC_SetPriority (USB_IRQn, 1);         /*2nd priority--is it correct??*/

void QEI_IRQHandler(void){
        USB_INT32S  fdw;
        fdw = FILE_Open(FILENAME_W, RDWR);
        if (fdw>0) {
                *UserBuffer=LPC_QEI->QEITIME;
                FILE_Write(fdw,UserBuffer,4);
                FILE_Close(fdw);
        }else{
                return;
        }
        LPC_QEI->QEICLR = 0xFFFFFFFF;   // clear all interrupts
}

Is it correct set priority of USB to 0 and QEI to 1??

kind regards

> LPC_QEI->FILTER =???(What should i put??

The time constant of the passive input RC (LC) filter is determined by the PCLK frequency of QEI.
It's much less than (1/8 - 1/16) of PCLK
QEI FILTER register holds a minimum expected interval of encoder transition, counted in PCLK scale.

> Is it correct set priority of USB to 0 and QEI to 1??

QEI should have the highest priority (0), and USB is assigned to lower priority than QEI.

> I have written below codes to send the data to usb using usbhost lite.

FILE_Open, FILE_Write and FILE_Close are too slow to run in the QEI ISR.
Also, it is efficient to write data of sector size at a time.

In the QEI ISR, the timer value is written to a buffer of 1024 bytes.
When the buffer holds 512 bytes (sector size) or more, one sector of data is written to the USB drive.

Tsuneo

>The time constant of the passive input RC (LC) filter is determined by the PCLK frequency of QEI.
It's much less than (1/8 - 1/16) of PCLK

So, if i want to filter pulses less than 2us, what should i write?(clk=100mhz)
LPC_QEI->FILTER =0xc8; /*200*/
Is it correct?

>When the buffer holds 512 bytes (sector size) or more, one sector of data is written to the USB drive.

Oh, I am a beginner!
I don't know how to access to the buffer. How can i get access to this Buffer?
what should i write instead of *UserBuffer=LPC_QEI->QEITIME; ??
can you help me with the codes?
thanks

>When the buffer holds 512 bytes (sector size) or more, one sector of data is written to the USB drive.

Thanks Dr Tsuneo Chinzei

But how can i detect that number of bytes written in QEITIME is 512?
And how to Empty the buffer after writing data?

An other Question: Is it correct to write LPC_QEI->FILTER =0xc8; /*200*/ to filter less than 2us when clock is 100mhz?

Best Regards?

I still haven't got answered my previous questions!
I don't know how to get access to the buffer that included timer(QEITIME) values?

another question:
what is the practical difference between set register & enable register(QEISET & QEIIES)? Can you give me an example please?

Amir
hejazi1365[at]gmail[dot]com
Best regards