C8051F987-GMR Silicon Labs, C8051F987-GMR Datasheet - Page 156

• Manufacturer Part Number: C8051F987-GMR
• Description: 8-bit Microcontrollers - MCU 8kB 512B RAM
• Manufacturer: Silicon Labs

Specifications of C8051F987-GMR

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

C8051F99x-C8051F98x
14.5.2. 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
14.5.3. System Clock
1. If operating from an external crystal, be advised that crystal performance is susceptible to electrical
2. If operating from the external oscillator, switch to the internal oscillator during Flash write or erase
Additional Flash recommendations and example code can be found in “AN201: Writing to Flash from Firm-
ware", available from the Silicon Laboratories web site.
156
exactly one routine in code that sets PSWE to a 1 to write Flash bytes and one routine in code that sets
both PSWE and PSEE both to a 1 to erase Flash pages.
and loop 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 website.
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.
interference and is sensitive to layout and to changes in temperature. If the system is operating in an
electrically noisy environment, use the internal oscillator or use an external CMOS clock.
operations. The external oscillator can continue to run, and the CPU can switch back to the external
oscillator after the Flash operation has completed.
Rev. 1.1