CHAPTER 4 INTERFACES
PRELIMINARY
NEC confidential and Proprietary
133
4.3.3 Transmit
operation
The
µ
PD98413 supports both the direct status indication mode (Byte-level mode) and the status polling mode
(Packet-level mode). This mode is selectable by the APIMM bit of the MDDGEN register.
(1) Direct status indication (Byte-level mode)
The
µ
PD98413 implements a dedicated DTPA signal for each of the ports. DTPA0 corresponds to the port0,
while DTPA3 corresponds to the port3. The
µ
PD98413 also implements the STPA signal for selected port.
The transmit interface is controlled by the POS device using the TENB_B signal. All signals is updated and
sampled using the rising edge of TFCLK.
Figure 4-17 is an example of the transmit timing. The
µ
PD98413 indicates that the FIFO is not full by asserting
DTPA. DTPA remains asserted until the transmit FIFO is almost full. The FIFO availability information that
indicated by DTPA and STPA is programmable by the FTHT1 and FTHT2 register.
If DTPA is asserted and the POS device is ready to transfer the transmit data, it asserts TSX, deasserts TENB_B
and presents the port address on the TDAT bus. Subsequent data transfers with TENB_B low are treated as
packet data that is sent to the selected port. At any time, if the POS device does not have data to send, it can
deassert TENB_B. The TSOP and TEOP signals must be marked at the start and end of packets on the TDAT
bus. When TEOP is asserted, the valid bytes on the TDAT bus are specified by TMOD[1:0]. The POS device
can indicate that there is an error in the current packet by TERR. TERR must be asserted when TEOP is
asserted.
In the direct status indication mode, the PTPA and TADR[1:0] signals are not used.
Figure 4-15. Transmit Timing (Direct Status Indication)
TFCLK
TENB_B
TSOP
TEOP
TMOD[1:0]
TDAT[31:0]
B1-B4
X
0000
B5-B8
B41-B44 B45-B48 B49-B52
X
X
X
B53-B56
B57
X
11
TERR
X
STPA
X : Invalid
TSX
DTPA0
DTPA1
DTPA2
DTPA3
X
0001
B1-B4
B5-B8
TPRTY
X
X
X
X
X
X
X
Summary of Contents for NEASCOT-P65
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