I have one problem with SD card, When I test the card I get the result
"SD card detected
FAT not found!"
Card formated FAT16, 1Gb
It look that transmission between card and uC is unstable. Did You have any problems with MENU and EXIT keys?
Try to change power source for SD board not from 5V but from battery. 3V3 voltage regulator should handle this.
One of my collogues Polish from forum try to develop better solution for converter. As soon He will finish I try to publish it. This should allow to have more robust solution.
Thank you for quick replay.
Menu works fine, but I have swapped two keys + and -
'll check the external power
I wrote my answer so fast that, that when I read it now, I surprise that You have understand anything from it...
So, SD card share that same pins as EXIT and MENU keys. That can be first problem, but fortunately You don't have it.
Second one, is power supply. Voltage regulator used on main board, don't have to much reserves, so it can't sometimes handle additional devices. (That is probably Your problem). You can solve it by disconnecting +5V supply cable for SD and connecting it directly to battery in Your radio. If You have used over 100mA voltage regulator, it could handle this.
If You check this, then, please, post an info with results.
SD handling had changed from this issue, and I get no other response if it works or not... For me and other it works well.