Z0221524ASCR4508TR Zilog, Z0221524ASCR4508TR Datasheet - Page 28

• Manufacturer Part Number: Z0221524ASCR4508TR
• Description: IC MODEM CTRL 2400BPS 44VQFP
• Manufacturer: Zilog

Specifications of Z0221524ASCR4508TR

• Data Format: V.21, V.22, V.23, Bell 103, Bell 212A
• Baud Rates: 2.4k
• Interface: Serial
• Voltage - Supply: 4.5 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 44-LQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: Z0221524ASCR4508T

PS001907-0904
Command
#F
DTMF
Detection
Command
Table 3. AT Command Set (Continued)
Single Chip Modem with Integrated Controller, Data Pump, and AFE
Function and Description
#F is used to detect DTMF digits received by the modem when it is off-hook in
the COMMAND state. #F does not operate during a data connection. The #F
command can only be entered from the command state and assumes that the
phone is off-hook. For example, to dial a call and then immediately enter the
DTMF detection mode the following series of steps are taken:
1. Send ATDxxxxx; command where xxxxx is the phone number.
2. Wait for the OK response.
3. Send AT#F1 to the modem.
4. You are now in the DTMF detection mode.
During DTMF detection the modem decodes received DTMF tones and issues
a line of ASCII text to the terminal each time a DTMF digit is detected.
DTMF Digit
The following table describes the output text according to which pair of DTMF
high and low tones were detected.
High band/
Low band
697 Hz
770 Hz
852 Hz
941 Hz
#F0
#F1
A–D
0–9
*
#
1
4
7
10
1209 Hz 1336 Hz 1477 Hz 1633 Hz
Detect DTMF digits with out using a human speech filter.
DTMF digits as short as 50 ms can be detected.
Detect DTMF digits while using a filter that reduces the
effect of human speech on the detection of DTMF digits,
improving the accuracy of detection. DTMF digits as short
as 60 ms can be detected.
2
5
8
0
3
6
9
11
Output Text
12–15
0–9
10
11
12
13
14
15
AT Command Set
Z02215
22