随记

尝试一下日记模板 看看可不可用

for i in range(1,2):
	try:
		i == 2
	except:
		i is 2
	break
	

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产测问题

uPD720201 USB controller 下挂的SPI rom 产测发现初始化失败，问题率100% 研发因2ndsource测试时产线未rwk，依旧测试主料，导致该物料没有做引入测试

rom物料如下： 主料Macronix MX25V5126F 替代料winbond W25X05CL

问题根因： 主料 与 替代料 在 PIN 7 存在差异 主料为NC , 替代料为 HOLD ，主板上拉电阻为CN=N 状态 替代料 PIN7 HOLD拉低时，CS & CLK 都为低状态，IC会进入hold模式，此时 DO为高电平，DI CLK会为忽略，导致USB controller无法读取ROM信息，造成USB controller 初始化失败。

原文如下：

W25X05CLSNIG 资料页 Q7. How does the /HOLD function of W25X05CLSNIG interact with the SPI bus?

A7. The /HOLD pin allows an active SPI transaction to be paused without deselecting W25X05CLSNIG. When /HOLD goes low while /CS is low and CLK is low (or after CLK falls), the device enters a hold state: DO is high‑impedance and DI, CLK are ignored. When /HOLD goes high with CLK low (or after the next falling edge), normal operation resumes from the exact bit position where it was paused. This mechanism is especially useful when several devices share the SPI bus and the bus master needs to temporarily redirect communication.