UPD72850A データシートの表示（PDF） - NEC => Renesas Technology
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UPD72850A Datasheet PDF : 48 Pages
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µPD72850A
4.6 Transmit
The µPD72850A arbitrates the serial bus using Link’s LREQ.
• When the µPD72850A acquires the bus, a Grant period of 1 SCLK is executed to CTL0,CTL1. After that, an Idle
period of 1 SCLK cycle is executed.
• Link controls the interface executing Idle, Hold of Transmit to CTL0,CTL1 after 1 SCLK cycle when Grant from
PHY is detected.
• Before asserting Hold and Transmit, assert 1 Idle cycle. Do not execute Idle for 2 or more cycles.
• If the packet transmit is not ready, the Hold period can be extended up to MAX_HOLD.
• The µPD72850A outputs DATA_PREFIX to the serial bus while Hold is being asserted to CTL.
• When the packet transmit is ready, Link outputs the first bit of the packet and Transmit is asserted to CTL at the
same time.
• After transmitting the last bit of the packet, Link outputs for Idle or Hold to CTL for 1 cycle. After that, it outputs
Idle for 1 cycle.
When PHY/Link releases the bus, output Low to CTL and D0-D7 within 1 cycle.
Figure 4-6. Transmit Timing
(a) Single Packet
PHY CTL0,CTL1
00 11 00 ZZ ZZ
PHY D0-D7
00 00 00 ZZ ZZ
Link CTL0,CTL1
ZZ ZZ ZZ 00 01
Link D0-D7
ZZ ZZ ZZ 00 00
ZZ ZZ ZZ ZZ
ZZ ZZ ZZ ZZ
01 10 10 10
00 D0 D1 D2
ZZ ZZ ZZ 00
ZZ ZZ ZZ 00
10 00 00 ZZ
Dn 00 00 ZZ
(b) Concatenated Packet
PHY CTL0,CTL1
ZZ ZZ ZZ ZZ 00
PHY D0-D7
ZZ ZZ ZZ ZZ 00
Link CTL0,CTL1
10 10 01 00 ZZ
Link D0-D7 Dn-1 Dn SP 00 ZZ
00 11 00 ZZ ZZ
00 00 00 ZZ ZZ
ZZ ZZ ZZ 00 01
ZZ ZZ ZZ 00 00
ZZ ZZ ZZ
ZZ ZZ ZZ
01 10 10
00 D0 D1
Note In case of packet transmission after Grant, before actual transmission, Hold does not need to be asserted.
Link can transmit continuous packets without releasing the bus.
• Hold is asserted to CTL. This function is used when the Link transmits continuous packets after acknowledge and
isochronous packets. Link outputs the transfer rate signal of the following packet to D0-D7 and asserts Hold
simultaneously.
• After Hold is detected by MIN_PACKET_SEPARATION, the µPD72850A outputs Grant to CTL.
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Data Sheet S14452EJ1V0DS00
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