AT90LS2323 ATMEL Corporation, AT90LS2323 Datasheet - Page 4

• Manufacturer Part Number: AT90LS2323
• Description: 8-bit Microcontroller
• Manufacturer: ATMEL Corporation

Table 1 summarizes the differences in features of the two
devices.
Table 1. Feature Difference Summary
Pin Descriptions AT90S/LS2323
VCC
Supply voltage pin.
GND
Ground pin.
Port B (PB2..PB0)
Port B is a 3-bit bi-directional I/O port. Port pins can provide
internal pull-up resistors (selected for each bit).
RESET
Reset input. A low on this pin for two machine cycles while
the oscillator is running resets the device.
XTAL1
Input to the inverting oscillator amplifier and input to the
internal clock operating circuit.
XTAL2
Output from the inverting oscillator amplifier.
Pin Descriptions AT90S/LS2343
VCC
Supply voltage pin.
GND
Ground pin.
Port B (PB4..PB0)
Port B is a 5-bit bi-directional I/O port. Port pins can provide
internal pull-up resistors (selected for each bit). When the
device is clocked from an external clock source, PB3 is
used as the clock input.
RESET
Reset input. A low on this pin for two machine cycles while
the oscillator is running resets the device.
CLOCK
Clock signal input in external clock mode.
4
Part
On-chip oscillator
amplifier
Internal RC Clock
PB3 usable
PB4 usable
Startup time
AT90S/LS2323 and AT90S/LS2343
AT90S/LS2323
yes
no
never
never
1 ms / 16 ms
AT90S/LS2343
no
yes
internal clock mode
always
16 s fixed
Clock Sources
The AT90S/LS2323 contains an inverting amplifier which
can be configured for use as an on-chip oscillator, as
shown in Figure 3. XTAL1 and XTAL2 are input and output
respectively. Either a quartz crystal or a ceramic resonator
may be used. It is recommended to use the AT90S/LS2343
if an external clock source is used, since this gives an extra
I/O pin.
The AT90S/LS2343 can be clocked by an external clock
signal, as shown in Figure 4, or by the on-chip RC oscilla-
tor. This RC oscillator runs at a nominal frequency of 1
MHz (VCC = 5V). A fuse bit - RCEN - in the Flash memory
selects the on-chip RC oscillator as the clock source when
programmed ('0'). The AT90S/LS2343 is shipped with this
bit programmed.
Figure 3. Oscillator Connection
Figure 4. External Clock Drive Configuration