MSC-MOD20 > I2C > SD initialization command (I command) > no reply for 1st command after power on boot

This is for communication with GHI Electronics on ALFAT SoC.
( https://www.ghielectronics.com/community/forum/topic?id=23533 )

Environment

MSC-MOD20 (ALFAT SoC) SD card module
ALFAT SoC version 2.0.0
I2C Connection used

Related: http://qiita.com/7of9/items/e649fc649855daa0fcb4

Investigation

After investigations using UART, it seem that the I command would receive response withing 200msec or so with SD mounted.
http://qiita.com/7of9/items/c018b2fa3e3a62f8c556

I have captured the I2C waveforms using Analog Discovery 2.

I repeated the I2C reading after sending I command with the time range:

• start time: 13:02:40.240
• end time: 13:02:40.964

I did not receive !00 or other error numbers within the 720 msec.

This behavior (no reply) is hold only for the combination of the following.

• using I2C
• first I command after the power on boot

For other condition, there is no problem.

Waiting for 8 seconds before I command did not change the behavior.

It seems that retry with 200msec wait can avoid this problem as I wrote in other article.
http://qiita.com/7of9/items/e649fc649855daa0fcb4