Samsung S5PC110 Manual page 950

S5PC110_UM
5.8.7.10 Device Threshold Control Register (DTHRCTL, R/W, Address = 0xEC00_0830)
Thresholding is not supported in Slave mode and so this register must not be programmed in Slave mode.
DTHRCTL Bit
Reserved [31:28] -
ArbPrkEn [27]
Reserved [26]
RxThrLen [25:17] Receive Threshold Length
RxThrEn [16]
Reserved [15:13] -
AHBThrRatio [12:11] AHB Threshold Ratio (AHBThrRatio) These bits define the
TxThrLen [10:2]
Arbiter Parking Enable.
This bit controls internal DMA arbiter parking for IN
endpoints. When thresholding is enabled and this bit is set
to one, then the arbiter parks on the IN endpoint for which
there is a token received on the USB. This is done to avoid
getting into underrun conditions. By default the parking is
enabled.
-
This field specifies Receive thresholding size in DWORDS.
This field also specifies the amount of data received on the
USB before the core can start transmitting on the AHB. The
threshold length has to be at least eight DWORDS. The
recommended value for ThrLen is to be the same as the
programmed AHB Burst Length (GAHBCFG.HBstLen).
Receive Threshold Enable
When this bit is set, the core enables thresholding in the
receive direction.
ratio between the AHB threshold and the MAC threshold
for the transmit path only. The AHB threshold always
remains less than or equal to the USB threshold, because
this does not increase overhead. Both the AHB and the
MAC threshold must be DWORD-aligned. If the AHB
threshold value is not DWORD-aligned after AHBThrRatio
is calculated (based on the application's programming of
the MAC threshold and AHBThrRatio), the core
automatically aligns to the next lower DWORD value.
When programming the TxThrLen and AHBThrRatio, the
application must ensure that the minimum AHB threshold
value does not go below 8 DWORDS to meet the USB
turnaround time requirements. • 2'b00: AHB threshold =
MAC threshold • 2'b01: AHB threshold = MAC threshold /
2 • 2'b10: AHB threshold = MAC threshold / 4 • 2'b11:
AHB threshold = MAC threshold / 8
Transmit Threshold Length
This field specifies Transmit thresholding size in DWORDS.
This field specifies the amount of data in bytes to be in the
corresponding endpoint transmit FIFO, before the core can
start transmit on the USB. The threshold length has to be
at least eight DWORDS. This field controls both
isochronous and non-isochronous IN endpoint thresholds.
Description
5 USB2.0 HS OTG
R/W Initial State
- 4'h0
R/W 1'b1
- -
R/W 9'h8
R/W 1'b0
- -
R/W 2'h0
R/W 9'h8
5-74