Specifications

TC35 / TC37 Hardware Interface Description
TC35_37_HD_02_V03.10 - Released Page 49 of 92 21.12.2001
3.8.2.2 Using the SYNC pin to control a status LED
As an alternative to generating the synchronization signal, the SYNC pin can be used to
control a status LED on your application platform.
To avail of this feature you need to set the SYNC pin to mode 1 by using the AT^SSYNC
command. For details see the "AT Command Set".
When controlled from the SYNC pin the LED can display the following functions:
Table 16: Modes of the LED and associated functions
LED mode Function
Off
*)
TC35/TC37 is off, in SLEEP, Alarm or Charge-only mode.
600 ms On / 600ms Off
*)
No SIM card inserted or no PIN entered, or network search in progress,
or ongoing user authentication, or network login in progress.
75ms On / 3s Off
*)
Logged to network (monitoring control channels and user interactions).
No call in progress.
On Depending on type of call:
Voice call: Connected to remote party.
Data call: Connected to remote party or exchange of parameters while
setting up or disconnecting a call.
*)
LED Off = SYNC pin low. LED On = SYNC pin high (if LED is connected as illustrated in Figure 19)
To operate the LED a buffer, e.g. a transistor or gate, must be included in your application. A
sample configuration can be gathered from Figure 19. Power consumption in the LED mode
is the same as for the synchronization signal mode. For details see Table 18, pin number 32.
Figure 19: LED Circuit (Example)