C8051F581-IMR Silicon Labs, C8051F581-IMR Datasheet - Page 142

• Manufacturer Part Number: C8051F581-IMR
• Description: 8-bit Microcontrollers - MCU 50MIPS 128kB 8kB SPI
• Manufacturer: Silicon Labs

Specifications of C8051F581-IMR

• Rohs: yes
• Core: 8051
• Processor Series: C8051
• Data Bus Width: 8 bit

C8051F58x/F59x
15.4. Flash Write and Erase Guidelines
Any system which contains routines which write or erase Flash memory from software involves some risk
that the write or erase routines will execute unintentionally if the CPU is operating outside its specified
operating range of V
fying code can result in alteration of Flash memory contents causing a system failure that is only recover-
able by re-Flashing the code in the device.
The following guidelines are recommended for any system which contains routines which write or erase
Flash from code.
15.4.1. V
1. If the system power supply is subject to voltage or current "spikes," add sufficient transient protection
2. Make certain that the minimum V
3. Enable the on-chip V
4. As an added precaution, explicitly enable the V
5. Make certain that all writes to the RSTSRC (Reset Sources) register use direct assignment operators
6. Make certain that all writes to the RSTSRC register explicitly set the PORSF bit to a 1. Areas to check
15.4.2. PSWE Maintenance
1. Reduce the number of places in code where the PSWE bit (b0 in PSCTL) is set to a 1. There should be
2. Minimize the number of variable accesses while PSWE is set to a 1. Handle pointer address updates
3. Disable interrupts prior to setting PSWE to a 1 and leave them disabled until after PSWE has been
4. Make certain that the Flash write and erase pointer variables are not located in XRAM. See your
5. Add address bounds checking to the routines that write or erase Flash memory to ensure that a routine
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devices to the power supply to ensure that the supply voltages listed in the Absolute Maximum Ratings
table are not exceeded.
this rise time specification, then add an external V
holds the device in reset until V
below the minimum threshold.
possible. This should be the first set of instructions executed after the Reset Vector. For C-based
systems, this will involve modifying the startup code added by the C compiler. See your compiler
documentation for more details. Make certain that there are no delays in software between enabling the
V
found in “AN201: Writing to Flash from Firmware", available from the Silicon Laboratories web site.
source inside the functions that write and erase Flash memory. The V
should be placed just after the instruction to set PSWE to a 1, but before the Flash write or erase
operation instruction.
and explicitly DO NOT use the bit-wise operators (such as AND or OR). For example, "RSTSRC =
0x02" is correct. "RSTSRC |= 0x02" is incorrect.
are initialization code which enables other reset sources, such as the Missing Clock Detector or
Comparator, for example, and instructions which force a Software Reset. A global search on "RSTSRC"
can quickly verify this.
exactly one routine in code that sets PSWE to a 1 to write Flash bytes and one routine in code that sets
PSWE and PSEE both to a 1 to erase Flash pages.
and loop variable maintenance outside the "PSWE = 1;... PSWE = 0;" area. Code examples showing
this can be found in ”AN201: Writing to Flash from Firmware" available from the Silicon Laboratories
web site.
reset to 0. Any interrupts posted during the Flash write or erase operation will be serviced in priority
order after the Flash operation has been completed and interrupts have been re-enabled by software.
compiler documentation for instructions regarding how to explicitly locate variables in different memory
areas.
called with an illegal address does not result in modification of the Flash.
DD
monitor and enabling the V
DD
Maintenance and the V
DD
, system clock frequency, or temperature. This accidental execution of Flash modi-
DD
monitor and enable the V
DD
DD
DD
DD
reaches the minimum threshold and re-asserts RST if V
monitor as a reset source. Code examples showing this can be
rise time specification of 1 ms is met. If the system cannot meet
monitor
Rev. 1.2
DD
DD
DD
monitor and enable the V
monitor as a reset source as early in code as
brownout circuit to the RST pin of the device that
DD
monitor enable instructions
DD
monitor as a reset
DD
drops