Texas Instruments TMS320C6457 manual Case 2 Autoincrementing Selected, FIFO Empty Before Write

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Figure 24. HRDY Behavior During a Data Write Operation in the 32-Bit Multiplexed Mode

(Case 2: Autoincrementing Selected, FIFO Empty Before Write)

HPIA Write

HPID+ Writes

HCSA

HCNTL[1:0] 10 01 01 01

HR/W

Internal

HSTRB

HD[31:0]

HRDY

A HCS may be brought high during strobe cycles. However, note that HRDY is gated by HCS.

Figure 25 shows an HPIA (HCNTL[1:0] = 10b) write access when the write FIFO is not empty, followed by several autoincrementing HPID (HCNTL[1:0] = 01b) write accesses. Note that HRDY is active twice for the HPIA access. This occurs because the FIFO is not empty and the data in the FIFO must first be written to memory. This results in an HRDY assertion immediately after the falling edge of the datastrobe (HSTRB). When a write request to memory has been made that will empty the internal FIFO, the HPIA write operation can complete with the rising edge of HSTRB. The second HRDY assertion is for the write to the HPIA register. HRDY is not active for the HPID accesses.

Figure 25. HRDY Behavior During a Data Write Operation in the 32-Bit Multiplexed Mode

(Case 3: Autoincrementing Selected, FIFO Not Empty Before Write)

HPIA Write

HPID+ Writes

HCSA

HCNTL[1:0] 10 01 01 01

HR/W

Internal

HSTRB

HD[31:0]

HRDY

A HCS may be brought high during strobe cycles. However, note that HRDY is gated by HCS.

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

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