Technologic Systems TS-7200, Руководство пользователя, Страница: 26 / 52

7 Real-Time Clock
The TS-7200 has an option for a Non-volatile Battery-backed real-time clock (RTC).
This option (TS-5620) is very low-cost daughter board that is only 1.1 x 3.5 inches (2.8 x
9.0 cm) and uses an ST Micro M48T86PC1 module for the real-time clock function. This
module contains the lithium battery, 32.768 kHz crystal, and a RTC chip with 114 bytes
of battery-backed CMOS RAM. It is guaranteed to maintain clock operation for a
minimum of 10 years in the absence of power.
The 114 bytes of non-volatile RAM that is located inside the RTC chip is not reserved
for TS-7200 functionality. This RAM is available for any user functions as required. Call
Technologic Systems for driver support.
The schematic for the TS-5620 is posted on our web site. The TS-5620 design only
uses two chips. This circuitry can be freely used on any customer daughter board
design if the battery-backed RTC feature is necessary.
The RTC is accessed using two registers. The write-only index register is located at
physical address location 0x1080_0000 and the RTC data register is location at
physical address location 0x1170_0000. These are byte-wide registers with the index
register being write only and the data register being read/write. Valid index register
values are between 0 and 127 decimal. The first 14 index locations are used for
accessing the RTC time and date registers.
The next 114 locations are non-volatile RAM locations.
TS-7200 User's Manual Technologic Systems http://www.embeddedARM.com/
22 12/2004