QSC K.2 Series Service Manual page 15

Input/DSP board
The input section consists of three separate inputs (MIC/LINE, LINE/INST, and AUX STEREO) which are summed together
before entering an audio codec that transmits the digitized audio to the DSP. The integrated DSP is configured to process
the incoming audio signal and finely tune it (low/high pass filtering, EQ, limiting, compression, and more) before outputting
the signal(s) to the amplifier stages. Due to this tuning, the K8.2, K10.2, and K12.2 amplifier modules cannot be inter-
changed between each other unless their DSP firmwares are changed. There is also a microprocessor on the input/DSP
board which manages the LCD display, LEDs, buttons, and rotary encoder.
ACV_MON
ACV_MON
TEST
TEST
DSP_RST_L
DSP_RST_L
CS_L_DSP
CS_L_DSP
MOSI
MOSI
SCLK
SCLK
TEMP_SENS
TEMP_SENS
SDTI
SDTI
2.5VREF
2.5VREF
MIC_LINE_SEL
MIC_LINE_SEL
LINE_INST_SEL_P
LINE_INST_SEL_P
LINE_INST_SEL_N
LINE_INST_SEL_N
LEDS_ON
LEDS_ON
AMP_SD_L
AMP_SD_L
Figure 4.3.8 - Block diagram of the input/DSP board, showing the MCU, DSP, and Codec signals
LCD board
The LCD board contains a monochrome display, microUSB connec-
tor, USB/I2C controller, rotary encoder, two navigational buttons, and
debouncer circuitry. The USB controller allows for communication over
the I2C bus between a computer and the microcontroller on the input/
DSP board. The rotary encoder and buttons are read by the microcon-
troller, so a debouncer circuit is implemented to reduce error. Physical
contacts can connect and disconnect multiple times during a button
push or release, so a debouncer circuit cleans up the inputs to the
microcontroller.
The LCD board is powered by the 3.3V rail, which originates on the
input/DSP board and comes into the LCD board at connector J1:pin4.
The 5V bus on the microUSB connector does not provide any power
to other circuits in the amplifier module, and is only monitored by the
USB/I2C controller.
TD-001517-01
K.2 Series Service Manual
DSP
AMP_SD_L
AMP_SD_L
MOSI
FAN_GND SCLK
FAN_GND
MISO
MISO
FAN_CTRL
FAN_CTRL
LIMIT_LED
LIMIT_LED
MCLK
MCLK
BICLK
BICLK
LRCLK
LRCLK
SDTO
SDTO
CODEC_CS_L
CODEC_RST_L
DOUBLER_RELAY
DOUBLER_RELAY
LEDS_ON_C
LEDS_ON_C
INPUTS
MIX_OUT_P
MIX_OUT_P
MIX_OUT_N
MIX_OUT_N
MIX_OUT2_P
MIX_OUT2_P
MIX_OUT2_N
MIX_OUT2_N
LEDS_ON_C
LEDS_ON_C
DISPLAY_AND_GPIO
CS_L_LCD ENC_A
CS_L_LCD ENC_A
MOSI ENC_B
MOSI ENC_B
SCLK BTN1
SCLK BTN1
FAN_CTRL BTN2
FAN_CTRL BTN2
LCD_A0
LCD_A0
LCD_RST_L TEST
LCD_RST_L TEST
LCD_BACKLIGHT
LCD_BACKLIGHT
SCL_I2C
SCL_I2C SWD_CLK
SDA_I2C
SDA_I2C SWD_DIO
SWD_RST
SWD_CLK
SWD_DIO
SWD_RST
MISO
ACV_MON
CODEC
MOSI
SCLK
HF_CH_P
MCLK HF_CH_P
HF_CH_GND
BICLK HF_CH_GND
LF_CH_P
LRCLK LF_CH_P
LF_CH_GND
SDTO LF_CH_GND
CODEC_CS_L
DOUBLER_RELAY
CODEC_RST_L
FRONT_LED
MIX_OUT_P
MIX_OUT_N
MIX_OUT2_P SDTI
MIX_OUT2_N
Figure 4.3.9 - LCD board
MICROCONTROLLER
MIC_LINE_SEL
ENC_A MIC_LINE_SEL
LINE_INST_SEL_P
ENC_B LINE_INST_SEL_P
LINE_INST_SEL_N
BTN1 LINE_INST_SEL_N
LCD_RST_L
BTN2 LCD_RST_L
LCD_A0
LCD_A0
TEST
CS_L_DSP
LCD_BACKLIGHT CS_L_DSP
CS_L_LCD
CS_L_LCD
FRONT_LED
FRONT_LED
REAR_LED
REAR_LED
MOSI
MOSI
SCLK
SCLK
DSP_RST_L
SWD_CLK DSP_RST_L
LEDS_ON
SWD_DIO LEDS_ON
SWD_RST
CODEC_CS_L
CODEC_CS_L
CODEC_RST_L
MISO CODEC_RST_L
ACV_MON
SCL_I2C
SCL_I2C
SDA_I2C
SDA_I2C
TO_AND_FROM_AMP
AMP_SD_L
TEMP_SENS
HF_CH_P
HF_CH_GND
LF_CH_P
LF_CH_GND
DOUBLER_RELAY ACV_MON
FRONT_LED
FAN_GND
FAN_GND
ACV_MON
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