Datasheet

MCP7940N
DS20005010F-page 26  2010-2014 Microchip Technology Inc.
REGISTER 5-14: CONTROL: RTCC CONTROL REGISTER (ADDRESS 0x07)
R/W-1 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
OUT SQWEN ALM1EN ALM0EN EXTOSC CRSTRIM SQWFS1 SQWFS0
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is clear x = Bit is unknown
bit 7 OUT: Logic Level for General Purpose Output bit
Square Wave Clock Output Mode (SQWEN =
1):
Unused.
Alarm Interrupt Output mode (ALM0EN = 1 or ALM1EN = 1):
Unused.
General Purpose Output mode (SQWEN = 0, ALM0EN = 0, and ALM1EN = 0):
1 = MFP signal level is logic high
0 = MFP signal level is logic low
bit 6 SQWEN: Square Wave Output Enable bit
1 = Enable Square Wave Clock Output mode
0 = Disable Square Wave Clock Output mode
bit 5 ALM1EN: Alarm 1 Module Enable bit
1 = Alarm 1 enabled
0 = Alarm 1 disabled
bit 4 ALM0EN: Alarm 0 Module Enable bit
1 = Alarm 0 enabled
0 = Alarm 0 disabled
bit 3 EXTOSC: External Oscillator Input bit
1 = Enable X1 pin to be driven by external 32.768 kHz source
0 = Disable external 32.768 kHz input
bit 2 CRSTRIM: Coarse Trim Mode Enable bit
Coarse Trim mode results in the MCP7940N applying digital trimming every 64 Hz clock cycle.
1 = Enable Coarse Trim mode. If SQWEN = 1, MFP will output trimmed 64 Hz
(1)
nominal clock signal.
0 = Disable Coarse Trim mode
See Section 5.6 “Digital Trimming” for details
bit 1-0 SQWFS<1:0>: Square Wave Clock Output Frequency Select bits
If SQWEN = 1 and CRSTRIM = 0:
Selects frequency of clock output on MFP
00 = 1 Hz
(1)
01 = 4.096 kHz
(1)
10 = 8.192 kHz
(1)
11 = 32.768 kHz
If SQWEN = 0 or CRSTRIM = 1:
Unused.
Note 1: The 8.192 kHz, 4.096 kHz, 64 Hz, and 1 Hz square wave clock output frequencies are affected by digital
trimming.