7 Host Interface Port
7 – 18
The following example shows the data that a host would write to the HIP
for a 1000-instruction boot:
Data
Location
Page Length (124 decimal)
HDR3
Upper Byte of Instruction at 999
HDR0
Lower Byte of Instruction at 999
HDR2
Middle Byte of Instruction at 999
HDR1
Upper Byte of Instruction at 998
HDR0
Lower Byte of Instruction at 998
HDR2
Middle Byte of Instruction at 998
HDR1
Upper Byte of Instruction at 997
HDR0
Lower Byte of Instruction at 997
HDR2
Middle Byte of Instruction at 997
HDR1
•
•
•
•
•
•
Upper Byte of Instruction at 0
HDR0
Lower Byte of Instruction at 0
HDR2
Middle Byte of Instruction at 0
HDR1
A 16-bit host boots the ADSP-21xx at the same rate as an 8-bit host. Either
type of host must write the same data to the same the HDRs in the same
sequence (HDR0, HDR2, HDR1). If a 16-bit host writes 16-bit data, the
upper byte of the data must be 0x00. The following example, loading the
instruction 0xABCDEF, illustrates this:
8-Bit Host
16-Bit Host
1st Write (to HDR0)
0xAB
0x00AB
2nd Write (to HDR2)
0xEF
0x00EF
3rd Write (to HDR1)
0xCD
0x00CD