Clever UARTs (Interrupt Driven)

http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/sad.gif

Hi Banx,

Thanx for your code. I&#39;ve compared it to mine and it is essentially the same. I&#39;ve even gone as far as re-writing my code the same as yours and trying it. The result remains the same. As soon as I enable the TRDY interrupt, the code breaks. It just doesn&#39;t make sense!!!

Just out of interest, I don&#39;t quite follow how the statement tx_in_index_0 &= txb_size_mask; works. I realise that you only use two pointers for your ring buffer. What do you determine by the statement??? (Please excuse my apparent stupidity!!!) I just use another variable as a counter. I suppose it boils down to being the same.

Out of interest, my current functions are:

// ============================================================

void uart_placechar(unsigned int uartnumber, unsigned char datacharacter)

{

while (uart[uartnumber].tx_counter == uart_tx_ringbuffer_size);

uart[uartnumber].tx_ringbuffer[uart[uartnumber].tx_wr_index] = datacharacter;

uart[uartnumber].tx_wr_index++;

if (uart[uartnumber].tx_wr_index == uart_tx_ringbuffer_size)

uart[uartnumber].tx_wr_index = 0;

// enable the tx (thr) interrupt

iowr_altera_avalon_uart_control(uart_base_address_lookup(uartnumber), (iord_altera_avalon_uart_control(uart_base_address_lookup(uartnumber)) | altera_avalon_uart_control_trdy_msk));

} // void uart_placechar(unsigned int uartnumber, unsigned char datacharacter)

// ============================================================

void uart25_isr(void* context, alt_u32 id)

{

unsigned char datacharacter;

unsigned int status,

uart_base_address,

uartnumber;

uartnumber = 25;

uart_base_address = uart_base_address_lookup(uartnumber);

status = iord_altera_avalon_uart_status(uart_base_address);

status &= (altera_avalon_uart_status_rrdy_msk | altera_avalon_uart_status_trdy_msk);

// clear any error flags and clear interrupt

iowr_altera_avalon_uart_status(uart_base_address, 0);

// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

// rx part

if (status & altera_avalon_uart_status_rrdy_msk)

{

datacharacter = iord_altera_avalon_uart_rxdata(uart_base_address);

if ((status & (altera_avalon_uart_status_fe_msk | altera_avalon_uart_status_pe_msk | altera_avalon_uart_status_roe_msk)) == 0)

{

uart[uartnumber].rx_ringbuffer[uart[uartnumber].rx_wr_index] = datacharacter;

if (++uart[uartnumber].rx_wr_index == uart_rx_ringbuffer_size)

uart[uartnumber].rx_wr_index = 0;

if (++uart[uartnumber].rx_counter == uart_rx_ringbuffer_size)

{

uart[uartnumber].rx_counter = 0;

uart[uartnumber].rx_buffer_overflow++;

} // if (++uart[uartnumber].rx_counter == uart_rx_ring_buffer_size)

} // if ((status & (altera_avalon_uart_status_fe_msk | altera_avalon_uart_status_pe_msk | altera_avalon_uart_status_roe_msk)) == 0)

} // if (status & altera_avalon_uart_status_rrdy_msk)

// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

// tx part

if (status & altera_avalon_uart_status_trdy_msk)

{

if (uart[uartnumber].tx_counter == 0)

{

iowr_altera_avalon_uart_control(uart_base_address, (iord_altera_avalon_uart_control(uart_base_address) | ~altera_avalon_uart_control_trdy_msk));

} // if (uart[uartnumber].tx_rd_index == uart[uartnumber].tx_wr_index)

else

{

iowr_altera_avalon_uart_txdata(uart_base_address, uart[uartnumber].tx_ringbuffer[uart[uartnumber].tx_rd_index]);

uart[uartnumber].tx_counter--;

uart[uartnumber].tx_rd_index++;

if (uart[uartnumber].tx_rd_index == uart_tx_ringbuffer_size)

uart[uartnumber].tx_rd_index = 0;

} // else

} // if (status & altera_avalon_uart_status_trdy_msk)

} // void uart25_isr(void* context, alt_u32 id)

Note: The function UART_Base_Address_Lookup(UARTNumber) just returns the base for the current UART. (In this way I can use the same code for all my UARTs, barring the ISRs, those are uniquely named but the body of the function remains the same. The only way I differentiate is by the "hardcoded" variable UARTNumber)

Also, I tried to se if my other UARTs are doing the same and they all are.

Regards,

Tyrone