Specifications

mikroElektronika | Free Online Book | PIC Microcontrollers | Chapter 8: Other MCU's Circuits
Fig. 8-16 Enabling Fail-Safe Clock Monitor
OSCTUNE Register
Modifications in the OSCTUNE register affect the HFINTOSC frequency, but not the LFINTOSC frequency. Furthermore,
there is no indication during operation that shift has occurred.
Fig. 8-17 OSCTUNE Register
TUN4 - TUN0 Frequency Tuning bits. By combining these five bits, the 8MHz oscillator frequency shifts. In this way, the
frequencies obtained by its division in the postscaler shift too.
TUN4 TUN3 TUN2 TUN1 TUN0 Frequency
0 1 1 1 1 Maximal
0 1 1 1 0
0 1 1 0 1
0 0 0 0 1
0 0 0 0 0 Calibrated
1 1 1 1 1
1 0 0 1 0
1 0 0 0 1
1 0 0 0 0 Minimal
Table 8-2 Frequency Tuning Bits
EEPROM
EEPROM is neither part of program memory (ROM) nor data memory (RAM), but a special memory segment. Even these
memory locations are not easily and quickly accessed as other registers, they are of great importance because the
EEPROM data are permanently saved (after the power supply goes off). EEPROM data can be also changed at any moment.
Because of these exceptional features, each byte of EEPROM is valuable.
The PIC16F887 microcontroller has 256 locations of data EEPROM controlled by the bits of the following registers:
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