TOOLSTICK560DC Silicon Laboratories Inc, TOOLSTICK560DC Datasheet - Page 101

• Manufacturer Part Number: TOOLSTICK560DC
• Description: DAUGHTER CARD TOOLSTICK F560
• Manufacturer: Silicon Laboratories Inc
• Series: ToolStickr
• Type: MCUr

Specifications of TOOLSTICK560DC

• Contents: Daughter Card
• Processor To Be Evaluated: C8051F55x, C8051F56x, C8051F57x
• Interface Type: USB
• Operating Supply Voltage: 2.7 V to 3.6 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: C8051F55x, C8051F56x, C8051F57x
• For Use With: 336-1345 - TOOLSTICK BASE ADAPTER336-1182 - ADAPTER USB DEBUG FOR C8051FXXX
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1719

C8051F55x/56x/57x
On the execution of the RETI instruction in the CAN0 ISR, the value in SFRPAGE register is overwritten
with the contents of SFRNEXT. The CIP-51 may now access the SPI0DAT register as it did prior to the
interrupts occurring. See Figure 12.6.
SFR Page 0xC
Automatically
popped off of the
stack on return from
interrupt
0x0
SFRPAGE
(SPI0DAT)
SFRNEXT
popped to
SFRPAGE
SFRNEXT
SFRLAST
Figure 12.6. SFR Page Stack Upon Return From CAN0 Interrupt
In the example above, all three bytes in the SFR Page Stack are accessible via the SFRPAGE, SFRNEXT,
and SFRLAST special function registers. If the stack is altered while servicing an interrupt, it is possible to
return to a different SFR Page upon interrupt exit than selected prior to the interrupt call. Direct access to
the SFR Page stack can be useful to enable real-time operating systems to control and manage context
switching between multiple tasks.
Push operations on the SFR Page Stack only occur on interrupt service, and pop operations only occur on
interrupt exit (execution on the RETI instruction). The automatic switching of the SFRPAGE and operation
of the SFR Page Stack as described above can be disabled in software by clearing the SFR Automatic
Page Enable Bit (SFRPGEN) in the SFR Page Control Register (SFR0CN). See SFR Definition 12.1.
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