Using EMI with DMA, possible ?

[markmcwired9]

Posted on September 19, 2007 at 08:17

Using EMI with DMA, possible ?

[markmcwired9]

Posted on May 17, 2011 at 09:46

Hi,

I want to send a buffer of 76800 bytes to the EMI, using DMA in two modes: 1) sending first the data pointer which indicates the byte's address in the buffer, using a counter for the address 2) sending only the data contained in the buffer with no address Are both tasks workable or impossible to do with the STR912 ? Does anyone have a working example to show how to do the previous tasks ? Thank you, Mark

[lodedeschepper]

Posted on May 17, 2011 at 09:46

Hi,

I succeeded to write to a display (attached on EMI0) by DMA. void DMA_Setup(void) { // Programming a DMA channel: see page 210 in the STR91xF reference manual DMA_Channel0->DES = (ulong)LcdDataRegister; // a fixed destination addres = the dataregister of the screen DMA_Channel0->LLI = 0x0; // we do not have a linked list to send (only one item: VideoBuf) // MEM -> PER, FLOW: DMA, DMA INT: EN DMA_Channel0->CC = 0x84000000 | GRAPHIC_BYTE_SIZE; // source increment DMA_Channel0->CCNF = 0x0000C880; DMA->CNFR = 0x01; // enable channel } void TIM_Setup(void) { // TIMER0: DMA TIM0->CR2 = 0x4400; // OC1IE = 1, resolution = fpclk/1 (increment counter register every 10.41ns) TIM0->OC1R = (u16)(0xFFFC + 0x0400); // 10.41 * 0x0400 = 10.6us (theoretical, (practical: 12.2) may not mutch less - else: last byte not on screen) NOW: 25ms for full screenupdate TIM0->CNTR = 0x0; // reset value to 0xFFFC TIM0->CR1 = 0x1000; // OC1 used as DMA source } void TIM0_IRQHandler(void) { TIM0->CNTR = 0x0; // reset counter TIM0->SR = 0x0; // clear status DMA->SBRR = 0x4; // not recomended!!!! VIC0->VAR = 0x0; VIC1->VAR = 0x0; } void DMA_IRQHandler(void) { TIM0->CR1 &= ~0x8000; // stop timer DmaFinished = TRUE; if (DMA->TCISR & 0x01) DMA->TCICR |= 0x01; if (DMA->EISR & 0x01) DMA->EICR |= 0x01; VIC0->VAR = 0x0; VIC1->VAR = 0x0; } When I start writing to the display: void CopyVideoMemoryToLcd(uchar *buf) { DmaFinished = FALSE; UpdateScreen = FALSE; WatchDog(); SetGraphicDisplayInAutoDataMode(); DMA_Channel0->SRC = (ulong)&VideoBuf; // a buffer with the data in the RAM DMA_Channel0->CC &= 0xFFFFF000; DMA_Channel0->CC |= GRAPHIC_BYTE_SIZE; // nmbr of bytes to transfer DMA_Channel0->CCNF |= 1; TIM0->CR1 |= 0x8000; // start DMA } This was the only solution that worked out for me... Hope this will help, Louis XIV