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This lesson is to understand the schematic diagram of the small audio, which is also the driver circuit of the speaker

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Look at Huawei P40 first, it uses the HiSilicon platform

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To find the small audio circuit of Huawei P40,

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we can start to search from the speaker connector J3701, and finally find the small audio core.

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Of course, we can also use other methods to find

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Open Xinzhizao's intelligent terminal maintenance query system and open the drawing of Huawei P40

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Search for SPK in the search box, let's see where it finds by default

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Codename GPIO means that it connects to the CPU

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SPK is related to speakers

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SMARTPA is a small audio, also called audio power amplifier

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This is an interrupt signal, which is an active low signal

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We double-click the code we just found to find the small audio

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It leads to the chip U3202

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Let's open the drawings of the P40 model to have a look

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We can find this chip by searching for U3202

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This chip is an audio power amplifier, SMARTPA

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Let's see if it's an audio amplifier

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This chip has a sound signal input, which is transmitted through the I2S bus

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The I2S bus has four wires

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There are clock, synchronization, and input and output signals

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Then this is the amplified signal used to drive the speakers

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This is the input sound signal of the I2S bus

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Let's take a look at this audio chip and have a comprehensive understanding of it

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We mentioned earlier that its working conditions include power supply, reset, I2S bus, I2S bus clock,

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synchronization, and input and output signals

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The two pins A4 and A5 are the I2C bus, which control the chip

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This is a 1.8-volt power supply for this small audio chip

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B5 pin here is the interrupt signal

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This GPIO is a general-purpose input and output interface, usually through the CPU

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In addition to these signals, let's look at the right side again

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The inductor on the right side is used by the booster circuit

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One end is connected to the main power supply, and the other end is connected to the internal,

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which is connected to the switching circuit

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This inductor cannot be short-circuited casually

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It also has a few capacitors, if they are corroded by water,

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they will easily cause a short circuit, and the short circuit will easily cause the chip to not work

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C3 and C5 pins are connected to the output signal

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E6 and E5 pins are voltage detection signals

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Let's check the wiring diagram and see where it goes from the speakers

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Let's copy it, paste it into the search box, hit search

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It leads to the speaker connector J3701

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There is no description of the speaker on the drawing, only the speaker connector

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Because its speaker is transmitted through the cable, this is the cable

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That's all for this lesson