Network Router User Manual

1st halfword
00 or 10 00 or 10
2nd halfword
Internal
HD[15:0]
HRDY
HHWIL
HR/W
HCNTL[1:0]
HCS
HSTRB
HCS
HCNTL[1:0]
HR/W
HHWIL
Internal
HSTRB
HD[15:0]
HRDY
1st halfword 2nd halfword 1st halfword
2nd halfword
11 111010
HPIA write HPID read
HCS
Internal
HRDY
HD[15:0]
HR/W
HCNTL[1:0]
HHWIL
10 10 01 01 01
1st halfword2nd halfword1st halfword2nd halfword1st halfword
HSTRB
HPIA write HPID+ reads
www.ti.com HPI Operation
The following sections describe the behavior of HRDY during HPI register accesses. In all cases, the chip
select signal, HCS, must be asserted for HRDY to go high.
3.9.1 HRDY Behavior During 16-Bit Multiplexed Read Operations
Figure 12 shows an HPIC (HCNTL[1:0] = 00b) or HPIA (HCNTL[1:0] = 10b) read cycle during 16-bit
multiplexed HPI operation. Neither an HPIC read cycle nor an HPIA read cycle causes HRDY to go high.
Figure 12. HRDY Behavior During an HPIC or HPIA Read Cycle in the 16-Bit Multiplexed Mode
Figure 13 includes an HPID read cycle without autoincrementing in the 16-bit multiplexed mode. The host
writes the memory address during the HPIA (HCNTL[1:0] = 10b) write cycle, and the host reads the data
during the HPID (HCNTL[1:0] = 11b) read cycle. HRDY goes high for each HPIA halfword access, but
HRDY goes high for only the first halfword access in each HPID read cycle.
Figure 13. HRDY Behavior During a Data Read Operation in the 16-Bit Multiplexed Mode
(Case 1: HPIA Write Cycle Followed by Nonautoincrement HPID Read Cycle)
Figure 14 includes an autoincrement HPID read cycle in the 16-bit multiplexed mode. The host writes the
memory address while asserting HCNTL[1:0] = 10b and reads the data while asserting HCNTL[1:0] = 01b.
During the first HPID read cycle, HRDY goes high for only the first halfword access, and subsequent HPID
read cycles do not cause HRDY to go high.
Figure 14. HRDY Behavior During a Data Read Operation in the 16-Bit Multiplexed Mode
(Case 2: HPIA Write Cycle Followed by Autoincrement HPID Read Cycles)
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SPRUGK7A–March 2009–Revised July 2010 Host Port Interface (HPI)
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