Hi, I am trying to use the USB2244 chip to access a SD card directly through a USB connector on my PCB board. I built the circuitry as shown in the image on a bread board. The SD card does not get detected on the PC. Only the driver is detected on the PC which is displayed as a greyed symbol of USB drive on the laptop. It would be great if somebody could help me with the mistake. I would really appreciate it. Best regards! Note: I am aware that the labels MISO/MOSI are incorrect and misleading as the connection to the SD card is not a SPI connection. However, the circuitry should work according to my understanding.
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Here is some addition: I am using USB to power up the USB2244. This line is connected to an LDO that steps down the voltage to 3.3V which is connected to all the input pins of the USB chip 6,14,22 and 36. I detected the following problem: There is no 1.8V observed at pin 13 and 34 which should normally be the case (1µF capacitors are connected as according to the data sheet).
Rene wrote: > the circuitry should work according to my understanding. Even without any clock? What voltage do you have at the reset pin? DS tells, that it must be at least 2V to recognize a "high".
Is the SD Card powered by the LM3480 as well? 100mA is way too little for an SD card.
That chip has a 24 MHz crystal in the datasheet that I am missing on your schematic.
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Jim M. wrote: > That chip has a 24 MHz crystal in the datasheet that I am missing > on > your schematic. You are absolutely right. In my last test it was missing. However, before I tried the same with a crystal connected and still it did not work. Niklas G. wrote: > Is the SD Card powered by the LM3480 as well? 100mA is way too > little > for an SD card. You are also absolutely right. I tried a different LDO (LM3940 with 1A max. output) and still it does not work. Still I do not get the desired 1.8V at pins 13 and 34 and do not get access to the SD card. See image below.
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