Cypress FX2LP User Manual
Page 6
February 19, 2008
Document No. 001-15342 Rev. **
6
AN6077
IOA = 0x80;
xFIFOTC_OUT = ( ( EP2FIFOBCH << 8 ) + EP2FIFOBCL );
// setup GPIF transaction count
SYNCDELAY;
EP2GPIFTCH = EP2FIFOBCH;
SYNCDELAY;
EP2GPIFTCL = EP2FIFOBCL;
// trigger FIFO write transaction(s)
SYNCDELAY;
GPIFTRIG = GPIFTRIGWR | GPIF_EP2;
// once master (GPIF) drains OUT packet, it (re)arms to usb domain
// this path is always auto, meaning core handles it
if( xFIFOTC_OUT < enum_pkt_size )
{
// handle short packet to peripheral
// wait for the transaction to terminate naturally
while( !( GPIFTRIG & 0x80 ) )
{
; // poll GPIFTRIG.7, DONE bit
}
// signal short packet to peripheral here
// in this implementation CTL2 is tied to PKTEND of slave strobe PKTEND of slave
GPIFIDLECTL |= 0x04;
GPIFIDLECTL &= 0xFB;
GPIFIDLECTL |= 0x04;
}
else
{
// was max packet size
// let transaction terminate naturally
}
}
else
{
// RDY1=0, when peripheral is FULL
}
}
}
else
{
// DONE=0 when GPIF is "not" IDLE
}
Expanded Master IN Code
// is the GPIF idle
if( GPIFTRIG & 0x80 )
{
// check if peripheral is "not empty"
if( GPIFREADYSTAT & 0x01 )
{
// RDY0=1, when peripheral is "not empty"
// drive FIFOADDR lines
OEA = 0xC0;
IOA = 0x00;