Buzzer - SimCom SIM900B Hardware Design

GND
KBC0
KBC1
KBC2
KBC3
KBC4
MODULE
KBR1
KBR2
KBR3
KBR4
*Note:
1. This function is not supported in the standard firmware. If user wants this function, the firmware must be customized. Please
contact SIMCom for more details.
2. KBR0&KBC0 are used to power off the module, so user can't connect these two pins as a key.
3. keypad is the second function of these pins, the default function is GPIO.

3.15 Buzzer

Features of buzzer:
10-bit resolution for buzzer tone frequency generation from 200 Hz to 5 kHz
Tone frequency error < 1 % for all standard piano notes from 200 Hz to 5 kHz
Tone level control from 0 dB down to −24 dB in +4 dB steps
Audio mute
The buzzer outputs a square wave at the desired tone frequency. The tone frequencies are programmable from 200
Hz to 5 kHz and can be re-programmed on-the-fly to generate monophonic audio ring tones or alert tones. The
tone level can be adjusted over a 24 dB range in 4 dB steps, or it can be muted.
For details, please refer to document[1]
SIM900B_Hardware Design_V2.01
Figure 31: Reference circuit of the keypad interface
33
Smart Machine Smart Decision
2012-05-07