Qc2.0 / 3.0 is the mobile phone fast charging protocol mainly promoted by Qualcomm in recent years. Thanks to the market share of chips in the mobile phone field, qc3.0 fast charging has been widely used in mainstream models such as Xiaomi and ZTE. This paper discusses the decoding of qc2.0 / 3.0 fast charging protocol with you.
1、 Introduction
Qc2.0 / 3.0 is a mobile phone fast charging protocol developed by Qualcomm in recent two years. Compared with the fast charging protocol of MediaTek and oppo, Qualcomm QC fast charging technology has the highest share in the field of smart phones. Qc2.0 is now becoming popular. The classA standard customized for smart phones supports 5V, 9V and 12V input voltages. On the basis of qc2.0, qc3.0 supports 200mV step-by-step gradual regulation voltage. At present, it has been supported in zds4000 full series oscilloscope for free. Users can download the latest firmware and upgrade it for free at Zhiyuan electronic network official.
2、 Protocol description
1. Protocol process
Figure 1 protocol flow
2. Voltage state
QC fast charging protocol uses the D + and d-pins of USB interface to describe different states through the change of three state voltage. The three states are 3.3V, 0.6V and GND respectively. The voltage status table is shown in Figure 2:
Figure 2 voltage status
3、 Decoding instance
Since the QC fast charging protocol needs to distinguish between 0.6V and GND, the vertical gear of the channel needs to be set to an appropriate position during decoding, which is recommended to be 1V / div or 500mv / Div. At the same time, because the waveform of the protocol generally lasts a long time, it is recommended to use roll mode to grab a long enough waveform, and then decode and analyze it under stop.
Recommended decoding steps:
(1) Set the vertical gear and offset of each channel to occupy the screen area as much as possible;
(2) Adjust the horizontal gear to enter the roll mode and grab the signal waveform for a certain length of time
