PmodRTCC™ Reference Manual
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The device is configured by writing to the registers within the device. The time registers can be set to specific
values and a control register sets their functionality.
Table 1. Pinout description table.
A full list of registers and their functionality, as well as communication specifications, can be found in the
MCP79410 datasheet available at the Microchip website.
The I
2
C interface standard uses two signal lines. These are I2C data (SDA) and serial clock (SCLK). These signals map
to the serial data (SDA) and serial clock (SCLK) on the MCP79410.
2.1 Power Back-up
The PmodRTCC has a holder for a 12mm lithium coin cell to power the RTCC and SRAM if VDD should ever fall
below the operating point. In order to enable this power back-up, the VBATEN bit must be set in the RTCC
registers. Compatible coin cells include BR1216, CR1216, BR1220, CL1220, CR1220, and BR1225.
Connector J1 – MFP Header
Table 2. MFP header.
2.2 Multi-Function Pin (MFP)
The MFP can be accessed via the 2-pin header J1. The MFP has an open drain output. To use it, an external 3.3V 2-
10K-ohm pull-up resistor is required.
The MFP can have several different functions including user-controllable output, alarm output, and clock
frequency output, depending on the settings in the RTCC registers. Settings and functions are described in the
MFP section of the MCP79410 datasheet.
2.3 Alarms
The MCP79410 has two alarms. Each can be set to trigger an alarm interrupt flag at a particular time, driving the
MFP high or low depending on how the polarity bit is set.
2.4 Calibration
The Calibration register in the MCP79410 can calibrate the device to correct for inaccuracies of the input clock
source. It can add or subtract up to 254 clocks from the RTCC counter every minute. For more information, see the
Calibration section of the MCP74910 datasheet.
