Initialization Of Hwob = 0 And Hpia - Texas Instruments TMS320C6201 Reference Manual

Host Access Sequences
Table 7–8. Initialization of HWOB = 0 and HPIA
Event HD
Host writes HPIC 0000
1st halfword
Host writes HPIC 0000
2nd halfword
Host writes HPIA 8000
1st halfword
Host writes HPIA 1234
2nd halfword
Note: A ? in this table indicates the value is unknown.
7.4.2 HPID Read Access Without Autoincrement
7-20
Value During Access
HBE[1:0] HR/W
xx 0
xx 0
xx 0
xx 0
Assume that once the HPI is initialized, the host wishes to perform a read ac-
cess to an address without an autoincrement. Assume that the host wants to
read the word at address 80001234h and that the word value at that location
is 789ABCDEh. Table 7–9 and Table 7–10 summarize this access for HWOB
= 1 and HWOB = 0, respectively. On the first halfword access, the HPI waits
for any previous requests to finish. During this time, HRDY pin is held high.
Then, the HPI sends the read request to the DMA auxiliary channel. If no pre-
vious requests are pending, this read request occurs on the falling edge of
HSTROBE. HRDY pin remains high until the DMA auxiliary channel loads the
requested data into HPID. Because all DMA auxiliary channel reads are word
reads, at the beginning of the second read access, the data is already present
in HPID. Thus, the second halfword HPID read never encounters a not-ready
condition, and HRDY pin remains active. The byte enables are not important
in this instance, because the HPI performs only word reads.
HCNTL[1:0] HHWIL
00 0
00 1
01 0
01 1
Value After Access
HPIC HPIA
00080008 ???????? ????????
00080008 ???????? ????????
00080008 8000???? ????????
00080008 80001234 ????????
HPID