VSBC-32
Functional Description
ID 21168, Rev. 04
Page 2 - 18
©
PEP Modular Computers GmbH
2.6 Special Board Functions
2.6.1
Real-Time Clock
The three-wire serial interface real-time clock V3021 is a 1-bit device which is accessi-
ble over the CS6 of the MC68(EN)360. Its time-keeping features include as follows:
•
seconds, minutes, hours, day of month, month, year, week day and week number in BCD
format;
•
leap year and week number correction;
•
stand-by supply smaller than 1µA.
For further information p
lease refer also to the “Software Configuration” chapter in this
manual and the EM Microelectronic V3021 data sheet.
2.6.2
EEPROM
T
he serial EEPROM is a 1-bit device which is accessible over the three-wire Interchip
SPI Interface of the MC68(EN)360. The first half of the EEPROM (1 kbit) is reserved for
factory data, including Board ID codes, Internet/Ethernet addresses, boot information
etc. The second half of the EEPROM is available for the user. See also the Software
Configuration chapter
in this manual.
For further information on the EEPROM, please refer also to the XICOR X25C02 data
sheet.
2.6.3
PLL Operation Mode
The MC68(EN)360 inputs EXTAL and CPU clock use the same input frequency. The
XTAL input is left open. The clock mode is selected via the hard-wired inputs MODCLK0
and MODCLK1. With the default settings of MODCLK0 = 1 and MODCLK1 = 0, the fol-
lowing configuration is selected:
•
no prescaler;
•
multiplication factor = 1;
•
CLKIN to the prescaler = CPU clock;
•
internal frequency (VCO/2) = CPU clock;
2.6.4
Tick Generator
The MC68(EN)360 internal Periodic Interrupt Timer is used by the
PEP real-time operat-
ing system as Tick generator.
For further information please refer also to the Motorola MC68(EN)360 User’s Manual.
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