TMS320C6727 Datasheet, PDF (55/115 Pages) Texas Instruments – Floating-Point Digital Signal Processors

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TMS320C6727, TMS320C6726, TMS320C6722
Floating-Point Digital Signal Processors
SPRS268C – MAY 2005 – REVISED NOVEMBER 2005
Figure 4-15 illustrates the Multiplexed Host Address/Data Half-Word Mode hookup between the C672x
DSP and an external host microcontroller. In this mode, each 32-bit HPI access is broken up into two
halves. The UHPI_HD[16]/HHWIL pin functions as UHPI_HHWIL which must be '0' during the first half of
access and '1' during the second half.
CAUTION
Unless configured as general-purpose I/O in the UHPI module, UHPI_HD[31:17] and
UHPI_HD[16]/HHWIL will be driven as outputs along with UHPI_HD[15:0] when the HPI
is read, even though only the lower half-word is used to transfer data. This can be
especially problematic for the UHPI_HD[16]/HHWIL pin which should be used as an
input in this mode. Therefore, be sure to configure the upper half of the UHPI_HD bus
as general-purpose I/O pins. Furthermore, be sure to program the UHPI_HD[16]
function as a general-purpose input to avoid a drive conflict with the external host
MCU.
In this mode, as well as the Multiplexed Host Address/Data Fullword mode, the UHPI can be made more
secure by restricting the upper 16 bits of the DSP addresses it can access to what is set in CFGHPIAMSB
and CFGHPIAUMB registers. (See Table 4-13 and Table 4-14).
The host is responsible for configuring the internal HPIA register whether or not it is being overridden by
the device configuration registers CFGHPIAMSB and CFGHPIAUMB.
After the HPIA register has been set, either a single or a group of autoincrementing accesses to HPID
may be performed.
The UHPI_HRDY adds wait states to extend the host MCU access until the C672x DSP has completed
the desired operation.
The HINT signal is available for the DSP to interrupt the host MCU. The UHPI also includes an interrupt to
the DSP core from the host as part of the HPIC register.
DSP
External Host MCU
EM_D[31:16]/UHPI_HA[15:0]^(A)
UHPI_HCNTL[1:0]
UHPI_HD[15:0]
UHPI_HD[16]/HHWIL
UHPI_HD[31:17]
UHPI_HAS^(B)
UHPI_HBE[1:0]^(C)
UHPI_HRW
UHPI_HDS[2]^(G)
UHPI_HDS[1]^(G)
UHPI_HCS
UHPI_HRDY
AMUTE2/HINT
NC
NC or GPIO
A[x:y]^(D)
D[15:0]
A[1]^(E)
BE[1:0]^(F)
R/W
WE^(G)
RD^(G)
CS
RDY
INTERRUPT
A. May be used as EM_D[31:16]
B. Optional for hosts supporting multiplexed address and data. Pull up if not used. Low when address is on the bus.
C. DSP byte enables UHPI_HBE[3:2] are not required in this mode.
D. Two host address lines or host GPIO if address lines are not available.
E. A[1], assuming this address increments from 0 to 1 between two successive 16-bit accesses.
F. Byte Enables (active during reads and writes). Some processors support a byte-enable mode on their write-enable
pins.
G. Only required if needed for strobe timing. Not required if CS meets strobe timing requirements. Tie UHPI_HDS[2] and
UHPI_HDS[1] opposite. For more information, see Figure 4-14.
Figure 4-15. UHPI Multiplexed Host Address/Data Half-Word Mode
Peripheral and Electrical Specifications
55