4d Systems SOMO 14D SOMO-14D SOMO-14D Data Sheet
Product codes
SOMO-14D
4D SYSTEMS SOMO-14D
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4. Pin Description
This section describes in detail the hardware
interface pins of the SOMO.
interface pins of the SOMO.
Micro-controller Interface Pins
4.1.
CLK pin 3 (Serial Data Clock):
Synchronous Clock Input. Each serial data bit is
latched into the module on the rising edge of the
clock. The idle state of the clock must be high.
When communication is required, the CLK is
brought LOW for a period of 2ms (START bit wait
time). Each individual data bit (starting with the
MSB bit15) is then clocked in sequentially. The
data is latched on every rising edge of the clock.
When the last data bit (bit0) is clocked in the CLK
signal must be held high for a period of 2ms (STOP
bit wait time) before the next command data is
sent. The clock HIGH and LOW periods are 100μs
minimum.
Refer to Section 9. Timing Diagrams for more
detailed timing and waveform information.
DATA pin 4 (Serial Data In):
Synchronous Data Input. The data is presented to
the module by the host micro via this pin. Each
command data is 16 bits wide. Data is serially
clocked in to the module starting with the most
significant bit (MSB bit15). Refer to Section 9.
Timing Diagrams for more detailed timing and
waveform information.
NOTE: For 5V systems, connect a series resistor
(100 to 470 Ohms range) on the CLK and DATA pins
between the SOMO and the target micro-
controller.
(100 to 470 Ohms range) on the CLK and DATA pins
between the SOMO and the target micro-
controller.
Key Interface Pins
4.2.
NEXT pin 1:
Selects the Next Audio file from the micro-SD
memory card. Active LOW triggered input.
Connect this pin to a push-button in stand-alone
KEY-MODE.
PLAY/STOP pin 6:
Play/Stop active LOW trigger Input. Connect this
pin to a push-button in stand-alone KEY-MODE.
Each active low trigger will alternate between
PLAY and STOP operation.
PREVIOUS pin 7:
Selects the Previous Audio file from the micro-SD
memory card. Active LOW triggered input.
Connect this pin to a push-button in stand-alone
KEY-MODE.
Connect this pin to a push-button in stand-alone
KEY-MODE.
Audio Output and Control Pins
4.3.
SPK+, SPK- pins 11, 12:
These pins provide a differential PWM+ and PWM-
output to a speaker. Connect these pins to an
8/16/32 Ohm (250mW) speaker.
These pins provide a differential PWM+ and PWM-
output to a speaker. Connect these pins to an
8/16/32 Ohm (250mW) speaker.
AUDIO pin 14:
External Amplifier Output pin. This pin provides a
16-bit DAC audio output to use with an external
audio amplifier. Example circuit below provides a
low cost implementation.
Figure 1: Optional Power Audio Circuit
Active high when SOMO plays an audio file and
active low when no file is played or stopped. This
pin can be used with a transistor arrangement to
filter out audible clicks when using the AUDIO
output with an external amplifier. It can also be
used to signal the host micro the end of the audio
file, in the serial mode.
System Pins
4.4.
RESET pin 10 (Module Master Reset):
Module Master Reset pin. Active LOW input.
Internally pulled up. After 1 second of a reset, the
module will go into low power standby mode
(8.0μA) if it detects no activity.
GND pin 9 (Module Ground):
Module ground pin. This pin must be connected to
ground.
VCC pin 8 (Module Supply Voltage Input):
Module supply voltage input pin. This pin must be
connected to a regulated supply voltage in the
range of 3.0 to 3.8 Volts DC. Nominal operating
voltage is 3.3 Volts. Connect a capacitor in the