User's Manual

Table Of Contents
MC55/56 Hardware Interface Description
Confidential / Preliminary
s
MC55/56_hd_v03.00 Page 46 of 104 16.08.2005
The /CTS signal is active low for 4.6 ms. This is followed by another 4.6 ms UART activity. If
the start bit of a received character is detected within these 9.2 ms, /CTS will be activated
and the proper reception of the character will be guaranteed.
/CTS will also be activated if any character is to be sent.
After the last character was sent or received the interface will remain active for
another 2 seconds, if AT+CFUN=5 or 7,
another 10 minutes, if AT+CFUN=6 or 8,
or for an individual time defined with AT^SCFG, if AT+CFUN=9. Assertion of RTS has the
same effect.
In the pauses between listening to paging messages, while /CTS is high, the module
resumes power saving and the AT interface is not accessible. See Figure 10 and Figure 11.
2.12 s
4.6 ms
4.6 ms
4.6 ms
4.6 ms
2.12 s
2.12 s
/CTS
AT interface disabled
AT interface enabled
Paging message Paging message Paging message
Paging message
4.6
ms
4.6
ms
4.6
ms
4.6
ms
Figure 10: Timing of /CTS signal (example for a 2.12 s paging cycle)
Figure 11 illustrates the CFUN=5 and CFUN=7 modes, which reset the /CTS signal 2
seconds after the last character was sent or received.
2.12 s
4.6 ms
2 s
4.6 ms
4.6 m
s
2.12 s
2.12 s
/CTS
AT interface disabled
AT interface enabled
1 character
st
Last character
Beginning of power saving
Paging message Paging message
Paging message
Paging message
4.6
ms
4.6
ms
Figure 11: Beginning of power saving if CFUN=5 or 7