Interrupts

[jamesadevine]

Hiya,

There's a comment in main.c that asks:

 * According to SDCC specification, interrupt handlers MUST be placed within the file which contains
 * the void main(void) function, otherwise SDCC won't be able to recognize it. It's not a bug but a feature.
 * If you know how to fix this, please let me know.

https://github.com/rikka0w0/CH55x_USB_CompositeDevice/blob/489bcf73a9872945ca642d420113aea2c8824348/main.c#L27

The SDCC specification actually states that interrupt handlers must be defined in main. The implementation of the function can exist elsewhere. See http://fivedots.coe.psu.ac.th/~cj/masd/resources/sdcc-doc/SDCCUdoc-11.html

I've also independently verified this assertion using some custom USB code on the CH554, compiled using SDCC. e.g.

void main()
{
    clock_init();
    uart1_init(1);
    usbd_init();

    LED_PORT_DIR |= LED_MSK;
    LED_PORT_PU &= ~(LED_MSK);

    while (1)
    {
        LED_PORT |= LED_MSK;
        wait_ms(500);
        LED_PORT &= ~LED_MSK;
        wait_ms(500);
    }
}

void usb_int(void) __interrupt(INT_NO_USB);

and in usbd.c:

void usb_int(void) __interrupt(INT_NO_USB) {
    ....

[jamesadevine]

Awesome work by the way @rikka0w0, thanks for sharing! It was great to have a functional USB stack to compare my dodgey one to during development.

[rikka0w0]

Thanks for the information!