开始这块板卡是好的,发现串口打印会死掉,就让工厂换CPU OMAP3520,现在测量 电源IC TPS65920B VMMC1 LDO 输入电压有,输出电压没有。这个IC没动,其它组电压测试正常,什么原因。
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HI
This LDO regulator can also be turned off automatically when MMC card extraction is detected.
(见datasheet第40页描述)
一般通过boot0~boot5来修改AM37xx的启动优先级,必须改为MMC1优先级最高,这样上电后就会先检测MMC1是否存在。
Using MMC1
The ROM code supports booting from MMC1, but only at 3.0V. If using a TPS659xx power companion chip, the ROM will command this chip to output 3.0V on VMMC1 when attempting to boot from MMC1. If you are not using a TPS659xx, you must ensure 3.0V is present when the ROM attempts to boot from MMC1.