User manual

...the world's most energy friendly microcontrollers
2012-04-24 - Giant Gecko Family - d0053_Rev0.96 281
www.energymicro.com
Figure 15.18. Normal Isochronous OUT/IN Transactions in DMA Mode
HostApplication DeviceAHB USB
O
U
T
D
A
T
A
0
M
P S
1
MPS
1
MPS
init_reg(ch_1)
init_reg(ch_2)
ch_2
ch_1
I
N
O
U
T
D
A
T
A
0
M
P S
Periodic Reque st
Queue
Assume that this
queue can hold
4 entries.
1
D
A
T
A
0
I
N
1
MPS
1
2
3
5
ch_1
2
4
5
init_reg(ch_1)
init_reg(ch_2)
init_reg(ch_1)
1
MPS
D
A
T
A
0
ch_2
4
3
Odd
frame
Even
frame
CHHLTD interrupt
CHHLTD interrupt
CHHLTD interrupt
Interrupt Service Routine for Isochronous OUT Transactions in DMA Mode
Isochronous OUT
Unmask (CHHLTD)
if (CHHLTD)
{
if (XFERCOMPL or FRMOVRUN)
{
De-allocate Channel
}
}
15.4.3.6.16 Isochronous IN Transactions in DMA Mode
To initialize the core after power-on reset, the application must follow the sequence in Overview:
Programming the Core (p. 248) . Before it can communicate with the connected device, it must initialize
a channel as described in Channel Initialization (p. 254) .