
iXPeRiPheRaLMoDuLes7(usB):usBFunCtionContRoLLeR(usB)
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iX-1-105
IX
USB
0x300995:DMa_Config_1(DMaConfiguration1)
name
address
Registername
Bit
setting
init. R/W
Remarks
D7
D6–4
D3
D2–1
D0
0
–
0
–
0
R/W
–
R/W
–
R/W
0 when being read.
00300995
(B)
DMa_Config_1
(DMa
configuration1)
RcvLimitMode
–
singleWord
–
CountMode
–
1 Receivelimitmode
0 Normal
1 Singleword
0 Multiword
1 Count-downmode
0 Free-runmode
This register sets fields on the operation mode of the DMA interface.
D7
RcvLimitMode
Setting this bit to 1 realizes the RcvLimit mode. This function is available only during write operation
for the asynchronous multi-word DMA transfer, and not available in the count down mode.
During the asynchronous DMA write operation in the RcvLimit mode, data up to 16 bytes can be
received even after this macro negates the PDREQ signal.
In this mode, the PDREQ signal is negated when the space of the endpoint becomes less than 32 bytes
by the DMA write operation. However, when the PDREQ signal is negated, 16-byte data that are not
written into the endpoint may exist in the internal circuit. Therefore, the data that can be received after
the PDREQ signal is negated, is 16 bytes or less.
In this mode, the PDREQ signal is negated before the endpoint becomes completely full.
When the area of the endpoint set by the EP{a,b,c,d}StartAdrs registers is the same as the value set by
the EP{a,b,c,d}MaxSize register (Single Buffer), the endpoint never becomes full. Therefore, the data
cannot be transmitted by the IN transfer of the USB.
To avoid this limitation, when using the RcvLimit mode, be sure to enter the value of the
EP{a,b,c,d}MaxSize register + 32-byte or larger area, into the EP{a,b,c,d}StartAdrs register.
D[6:4]
Reserved
D3
singleWord
Sets the handshake mode in the Asynchronous (handshake) mode.
In the Single Word mode, the PDREQ signal is negated every time when one word is transferred.
In the Multi-Word mode, the PDREQ signal is not negated if the next data communication is possible
when one word is transferred.
D[2:1]
Reserved
D0
CountMode
Sets the mode to control the number of the DMA transmissions.
In the free-run mode, the DMA transfer operation is continued until the DMA_Stop is enabled. The
Transfer Byte Counter (DMA_Count_HH, HL, LH, LL) shows the number of transmissions for
reference.
In the Count-down mode, the DMA transfer is continued up to the number of bytes set in the Transfer
Byte Counter (DMA_Count_HH, HL, LH, LL) or until the DMA_Stop is enabled to stop it. The
Transfer Byte Counter shows the remained transmission quantity, for reference.