S12 Clock, Reset and Power Management Unit (S12CPMU_UHV_V8)
MC9S12VRP Family Reference Manual Rev. 1.3
NXP Semiconductors
167
4.7.2
Application information for COP and API usage
In many applications the COP is used to check that the program is running and sequencing properly. Often
the COP is kept running during Stop Mode and periodic wake-up events are needed to service the COP on
time and maybe to check the system status
.
For such an application it is recommended to use the ACLK as clock source for both COP and API. This
guarantees lowest possible IDD current during Stop Mode
.
Additionally it eases software implementation
using the same clock source for both, COP and API
.
The Interrupt Service Routine (ISR) of the Autonomous Periodic Interrupt API should contain the write
instruction to the CPMUARMCOP register. The value (byte) written is derived from the “main routine”
(alternating sequence of $55 and $AA) of the application software
.
Using this method, then in the case of a runtime or program sequencing issue the application “main
routine” is not executed properly anymore and the alternating values are not provided properly. Hence the
COP is written at the correct time (due to independent API interrupt request) but the wrong value is written
(alternating sequence of $55 and $AA is no longer maintained) which causes a COP reset
.
If the COP is stopped during any Stop Mode it is recommended to service the COP shortly before Stop
Mode is entered.
Summary of Contents for MC9S12VRP64
Page 16: ...MC9S12VRP Family Reference Manual Rev 1 3 16 NXP Semiconductors ...
Page 46: ...Device Overview S12VRP Series MC9S12VRP Family Reference Manual Rev 1 3 46 NXP Semiconductors ...
Page 236: ...S12S Debug Module S12DBGV2 MC9S12VRP Family Reference Manual Rev 1 3 236 NXP Semiconductors ...
Page 244: ...Interrupt Module S12SINTV1 MC9S12VRP Family Reference Manual Rev 1 3 244 NXP Semiconductors ...
Page 358: ...Timer Module TIM16B2CV3 MC9S12VRP Family Reference Manual Rev 1 3 358 NXP Semiconductors ...
Page 436: ...Supply Voltage Sensor BATSV2 MC9S12VRP Family Reference Manual Rev 1 3 436 NXP Semiconductors ...
Page 528: ...NVM Electrical Parameters MC9S12VRP Family Reference Manual Rev 1 3 528 NXP Semiconductors ...
Page 530: ...Package Information MC9S12VRP Family Reference Manual Rev 1 3 530 NXP Semiconductors ...
Page 531: ...Package Information MC9S12VRP Family Reference Manual Rev 1 3 NXP Semiconductors 531 ...
Page 532: ...Package Information MC9S12VRP Family Reference Manual Rev 1 3 532 NXP Semiconductors ...