We are using VF50 on our carrier board, where power supply is given direct from a simple 3.3V DC/DC. When we try to disconnect power from connector and connect it again, often VF50 doesn’t boot and sometimes lost also registry contents.
This is the boot sequence
Toradex Bootloader 1.3 BETA 2 for Colibri Built Dec 15 2015
CPU: MVF50 400 Mhz
Flash: 128 MB
RAM: 128 MB
Using ECC Type: 7
Booting from fuses.
reading fuses OK.
Colibri VF50 module version 1.1A
Press [SPACE] to enter Bootloader Menu
Initiating image launch in 0 seconds.
Loading OS Image
…
Done.
OEMLaunch 80004000
Hi,
We noticed same issue if RX pin of UART0 is floating. We fixed it but we did not release it yet. You can try and pull RX up with a resistor. Also we recomend always using latest image. Currently 1.3BETA4 is avalible.
If I try to power on and the VF50 doesn’t boot, when I close reset it boot correctly, I thik is a problem of DC/DC converter and voltage ramp when I connect power. But VF50 hasn’t any reset circuit on board, I don’t provide it on my carrier board, in this way reset is hold low since voltage is good and stable.
The Colibri VFxx features a power on reset signal (POR). This reset is generated on the module when the main 3.3V is ramping up. After the release of the POR, the module starts booting.
The POR is is only generated, if the main 3.3V is going down to a certain voltage. If your module main 3.3V is not going down enough due to back feeding, this could lead to a problem. Therefore, I recommend you measuring the voltage level of the main 3.3V for the module during the switched off DC/DC converter. If the voltage is quite high, try to reduce it by reducing the back feeding trough driven IO pins.
