We are using jetson nano （b version）， and SD card function is under developing,
CD corresponds to GPIO8(core board is gpio8, tegra is p22).
Please confirm again, if the resistance is 0Ω, the system will crash, but when change the resistance to 1K, it works normal,but clock frequency is only 3MHZ.
The test clock is shown as figure 2, the highest voltage level is 1.8V. We have already added resistance on it, so it is not complete waveform. The voltage of SD card is 3.3V, it is shown as figure 1.
In addition, when it starts working, we can’t see the 3.3V waveform.
Could you please tell why this R294~300 needs to be changed to 1k resistance?
Do you have any documents about this SD card in details, or any circuit design documents?
Or we need to configurate it on the software?
Hi, are you following OEM DG to do design? There is no figure attached.
Yes,following Jetson_Nano_Product_Design_Guide, please see Attanchments
Hi, did you check the pinmux settings of all these pins? They should be set to correct function pin type.
Also your SCH looks different to DG:
- No need to add the resistors.
- There should be EN for 3.3v load switch.
- No need to add pull-up for CD.
1.I know this, but if the resistors is 0Ω, the system will crash.And change the resistors to 1K,it works normal,but clock frequency is only 3MHZ, I was very confused
2.Is it the key of this question ,I often do this in other project ,it’s OK.
3.I removed pull-up,but same as before
To keep same to guide is necessary, please use recommended EN for load switch first. And check the pinmux if all pins are set correctly.
Hi Trumany, I know it’s important to use recommended EN, but it’s not the key ,it’s just recommended,because it didn’t show me exactly which pin to connect to EN,please see the attachments .Is there other recommended about software ?This system is booting from EMMC ,and jetson nano A version is booting from SD card, it is difference.At first ,we can’t drive SD care，modify the driven software, SD card can be detected but the frame is just 3MHz.
Please also refer to this thread for software configuration.