Based on GL3224-QFN48 master control EMMC reading and writing solution

Quote: Some precautions are as follows:
1. The crystal oscillator can use an internal or external crystal oscillator, which will not cause a decrease in speed; 2. For SPI flash, choose a commonly used and easy-to-buy one, such as W25Q16.3. Do not use 1.2V and 3.3V magnetic beads for the power supply. If it is too large, it will cause insufficient power supply and cannot be used. 4. There are 3 pairs of lines that need to be differential lines. Each pair of lines does not need to be all the same length. Some differences will have little impact. DM and DP require differential lines. TXP and TXN require differential lines. RXP and RXN require differential lines. Differential lines The two lines are required to run parallel and equally spaced, and the spacing is about 8 mil. 5. DP and DM lines cannot be reversed, but RXP and RXN can be reversed, and TXP and TXN can be reversed. It is difficult to find some precautions for these lines online. In addition, RX means receiving, TX means sending, TX must be connected to the RX of the upstream device (computer), and RX must be connected to the TX of the upstream device (computer). 6. The TXP and TXN of GL3224 should be connected to the USB interface with a 104 capacitor, and the capacitor should be as close to the interface as possible. 7. The capacitor in the circuit should be as close to the chip pin as possible, not too far away. ————————————————