ST90158 - DEVICE ARCHITECTURE
SYSTEM REGISTERS (Cont’d)
USER STACK POINTER HIGH REGISTER
(USPHR)
R236 - Read/Write
SYSTEM STACK POINTER HIGH REGISTER
(SSPHR)
R238 - Read/Write
Register Group: E (System)
Reset value: undefined
Register Group: E (System)
Reset value: undefined
7
0
7
0
USP15 USP14 USP13 USP12 USP11 USP10 USP9 USP8
SSP15 SSP14 SSP13 SSP12 SSP11 SSP10 SSP9 SSP8
USER STACK POINTER LOW REGISTER
(USPLR)
R237 - Read/Write
SYSTEM STACK POINTER LOW REGISTER
(SSPLR)
R239 - Read/Write
Register Group: E (System)
Reset value: undefined
Register Group: E (System)
Reset value: undefined
7
0
7
0
USP7 USP6 USP5 USP4 USP3 USP2 USP1 USP0
SSP7 SSP6 SSP5 SSP4 SSP3 SSP2 SSP1 SSP0
Figure 11. Internal Stack Mode
Figure 12. External Stack Mode
REGISTER
FILE
REGISTER
FILE
STACK POINTER (LOW)
STACK POINTER (LOW)
&
points to:
F
F
STACK POINTER (HIGH)
point to:
MEMORY
E
E
STACK
D
D
STACK
4
3
2
1
0
4
3
2
1
0
28/199
9
ETC [ ETC ]
