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Bose Personalized Amplification System 문제 해결 매뉴얼

THEORY OF OPERATION

The MCU needs to transfer the clip state information to the remote control. The communication

protocol adopts hardware UART. The communication rate is 9600bps, Data is sent according to

MIDI protocol: MIDI channel number | MIDI parameter type | MIDI parameter value. DSP will

transfer a frame data every 100ms, and every sending will take about 3.5ms.

Relay of Remote information to the Power Stand DSP. The remote needs to transfer the

Ch1EQHi, Ch2EQHi, Ch1EQMi, Ch2EQMi, Ch1EQLo, Ch2EQLo, Ch1Volume, Ch1Volume, and

MasterVolume information to the power stand MCU PCB. The communication adopts hardware

UART. The communication rate is 9600bps, Data is sent according to the MIDI protocol: MIDI

channel number | MIDI parameter type | MIDI parameter value. DSP will transfer a frame data

every 100ms, and every sending will take about 30ms.

The power stand MCU PCB needs to transfer the Ch1EQHi, Ch2EQHi, Ch1EQMi, Ch2EQMi,

Ch1EQLo, Ch2EQLo, Ch1Volume, Ch1Volume, MasterVolume, Ch1Preset, Ch2Preset,

BassChk, and CheckSum information to the DSP. The communication adopts software simula-

tion UART, with two I/O pins as RX and TX. Communication rate is 4800bps, add start bit and

stop, so every sending byte has 10 bits. Data is sent according to frame format: every data |

check sum. DSP will transfer a frame every 100ms, and every sending will take about 30ms.

1.9 Software and User Interface

The Bose

Personalized Amplification System™ family of products has a simple user interface

which is mostly implemented in software. In this chapter we describe how most of the functions

are implemented.

1.9.1 Gain Staging

Gain staging is the process of properly adjusting the gain of the system. The goal is to set the

gains as high as possible (to optimized signal/noise) without overdriving or clipping any elec-

tronic components. In contrast to home-audio products, musical instrument and microphones

have a large variation of output gains and gain staging is typically required.

On Channel 1 and 2, the user needs to set the trim control on the power stand so that the

overload LED just turns red for the loudest anticipated input signals and then back up a little.

This is done purely in analog and the goal is to not overload the preamplifier.

Next the user should adjust the channel volume on the remote so that the LED on the remote

does not turn red. The LEDs are calibrated so that for sine wave input, nothing connected to the

insert loop, and the channel volume at the 12 o'clock setting both LEDs turn red at the same

level.

1.9.2 Channel Volume

The microcontroller polls the remote in regular intervals, about 10 times per second. The

microcontroller then maps the settings to a range from -40 to 0 dB and programs the volume

control chip U302 through its digital control interface. The volume control should span a range of

40 dB with a linear (in dB) range from -30dB to -10dB from all the way down to 12 o'clock and a

range from -10dB to 0dB for 12 o'clock to "all the way up" setting.

1.9.3 Tone Controls

The microcontroller polls the remote in regular intervals. The microcontroller transfers the tone

control settings to the DSP which implements them for each channel as shown in Figure 11.