Real time clock, I2c bus software emulation, Dc characteristics – Zilog EZ80190 User Manual
Page 56: C bus software emulation
eZ80190 Development Kit
User Manual
eZ80190 Module
UM014108-0810
52
Real Time Clock
The onboard real-time clock can function when the system power supply
is down. An onboard capacitor (GoldCap) or external accumulator/battery
serves as a standby power supply. The M41T11 Real-Time-Clock
included on the eZ80190 Module contains Binary Coded Decimal (BCD)
counting registers for Seconds, Minutes, Hours, Day, Month, Year; it also
contains a Century bit and 56 bytes of backed-up RAM. The fully-
charged 0.1 F GoldCap bridges power outages with a maximum of 4
hours. The GoldCap, in contrast to a battery or an accumulator, offers an
advantage in that service/replacement is not necessary.
The I
2
C address of the RTC is
D0h
for Writes and
D1h
for Reads.
Details about the internal registers of the M41T11 Real-Time clock can be
found on the ST Microelectronics website
I
2
C Bus Software Emulation
The eZ80190 device contains two powerful master/slave mode I
2
C bus
controllers. The I
2
C data (SDA) and clock (SCL) pins on PD1/PD0 and
PC1/PC0 GPIO are multiplexed with the UART and SPI functions. To use
I
2
C bus operation in parallel with console and modem I/O, the module
IICSCL/IICSDA pins on connector JP2 can be linked to PA7 (IICSDA)
and PA6 (IICSCL) of the eZ80190 device. In this case, an I
2
C master-
mode software emulation is necessary to access I
2
C devices.
Using PA7/PA6 or PC1/PC0 for IICSDA/IICSCL is resistor-selectable on
the eZ80190 Module.
DC Characteristics
As different combinations of application modules are loaded onto the
eZ80Acclaim!
®
Development Platform, current requirements change.
Please see
on page 43 to reference current consumption values
for these different modules.