ISM 868 MHz, 433 MHz and 315 MHz FSK Transmitter – Preliminary Data Sheet

ASCell3911

Rev. A, February 2000

Page 6 of 13

Austria Mikro Systeme International AG

SERIAL DATA OUT (P1)

STOP TRANSMIT (P4)

NCLEAR

CLK

µC_CLK

DATA

WAKEUP

10k

µC

10k

Transmit

button

SW

I

O

O

I/O

I/O

I

I

SERIAL DATA ENABLE (P2)

D_EN

I

O

SERIAL DATA CLOCK (P3)

D_CLK

I

O

Figure 3:

Interconnection of the ASCell3911 with a typical µC with one button to wake up the whole

system (example).

Note:

At room temperature, resistor values of

≈10 kΩ are suggested for the µC interface.

SW

µC_CLK

WAKEUP

P4

standby

startup

32 clocks

16 clocks

active/transmisson

4 clocks

standby

open

closed

SC3911

reset µC

power

down µC

µC

SC3911

startup

µC

Figure 4:

µC interface timing for wake-up and power down control.

Note:

The dashed lines indicate w eak high or low state when the µC_CLK or WAKEUP output of the ASCell3911 is disabled

(in high-resistive Z state) and pulled ”H” or ”L” by the internal pull-up device or by the µC via a resistor. These weak

states can be overridden by the ASCell3911 if the respective outputs are enabled. Whenever a line is pulled via an ex-

ternal resistor, however, this should override the internal pull-up devices of the ASCell3911.

1.6.1 Interface Description

It is assumed that the µC remains in low power standby mode as long as the P4 pin is kept ”L”

and no clock cycles are applied.

holds the µC in a reset state:

ASCell3911