STLC1502
7.9.2 Receive Message from ARM by Host Processor
After receiving interrupt from ARM:
• Clear Output Index Register (address b.001) by writing any value.
• Read message from Output Message Buffer by consecutively reading from its address (b.110). Each
read will cause the Output Index Register to increment by 1 and access another byte location.
• Clear the Output Status Reg (address b.000) by writing any value (the ARM can clear the OSR by
writing 0 to it).
7.9.3 Send Message from ARM to Host Processor
• Read Output Status Register. If h0001, the HP has not read out the last message. If 0x0000, the HP
has read the last message and the Output Message Buffer is available for use.
• Write message into Output Message Buffer. This buffer is directly addressable by the ARM.
• Write 0x0001 to Output Status Register to interrupt the HP
7.9.4 Receive Message from Host Processor by ARM
After receiving interrupt from HP:
• Read message from Input Message Buffer.This buffer is directly addressable by the ARM.
• Clear the Input Status Reg by writing 0x0001 to its address (the HP can clear the ISR by writing 0 to
it).
In the following table there is the list of the available external signals of the HPI interface.
NAME
HPI_CLK
HPI_CS
HPI_AS
HPI_RW
HPI_ADDR(2:0)
HPI_DATA(7:0)
HP_INT
7.9.5 HPI Memory map
Signal type
IN
IN
IN
IN
IN
INOUT
OUT
Description
HPI bus clock form Host Processor
Active low select from Host Processor.
Address strobe from Host Processor.
R/W from Host Processor
Host Processor address
Host Processor data bus lines.
Interrupt to Host Processor
Table : External signals of HPI
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