Texas Instruments TMS320C6457 manual Hrdy Behavior During 16-Bit Multiplexed Read Operations

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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.

3.9.1HRDY 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

HCS

HCNTL[1:0] 00 or 10 00 or 10

HR/W

HHWIL

Internal

HSTRB

HD[15:0] 1st halfword 2nd halfword

HRDY

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)

HPIA write

HCS

HPID read

HCNTL[1:0] 10 10 11 11

HR/W

HHWIL

Internal
HSTRB	1st halfword	2nd halfword	1st halfword	2nd halfword
HD[15:0]
HRDY

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)

HPIA write

HCS

HPID+ reads

HCNTL[1:0] 10 10 01 01 01

HR/W
HHWIL
Internal
HSTRB	1st halfword	2nd halfword	1st halfword	2nd halfword	1st halfword
HD[15:0]
HRDY

SPRUGK7A –March 2009 –Revised July 2010 Host Port Interface (HPI) 23

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