From: Dave H. <dhy...@gm...> - 2006-11-07 23:25:55
|
Hi Chris, On 11/7/06, Chris Evans <roo...@gm...> wrote: > Curioser and curioser... > > I thought that before I tried what you said I would remove the tweener board > and see if somehow that was causing part of the problem. My normal setup is > robotstix -> tweener -> gumstix -> wifistix. I plug 5v into the tweener and > everything works. When I remove the tweener now, nothing will boot. The blue > led on the robostix doesn't even flash (although all the green leds are lit) > and the wifistix never comes online. Whenever you use a robostix, you always need to at least provide power to the robostix. Normally, any of the power jacks is V_BATT and it doesn't matter which onw you plug into, since they're all connected up. Since the robostix will often be powered from batteries, and V_BATT can't exceed about 6v, the power jack on the robostix is called V_ROBOBATT, and it goes through a 5v regulator to become V_BATT. This allows a 9v battery to be used to power the robostix & gumstix. However, it means that if you plug power into say the tweener, then the gumstix will be properly powered, but the robostix will not. It will get partial power in the form of leakage current from lines connected to the gumstix. So: RULE 1: When using a robostix, make sure you plug the jack into the robostix. Also, the voltage regulator attached to the robostix can only provide 500ma, so some cards (like Wifi cards) don't work, because they try to draw too much current. When a robostix is plugged in and no tweener is used and no serial adapter is plugged into the gumstix jack, then you need to put a 10k resistor between 4 of the gumstix adapter and +5 from one of the UARTs pins. Some people have also had success putting the resistor beteen pins 3 & 4 of the gumstix connector. Failing to install the resistor will cause the boot to think that the user is causing a Break and it will drop into u-boot. By default, the robostix is held in reset when booting. You can perform the modifications mentioned on this page to get the robostix to run as the gumstix is booting: http://docswiki.gumstix.org/Robostix_uboot So you'd need to perform more tests taking the above into consideration before being able to figure out if the robostix is good or bad. Ideally, you'd do the following steps: 1 - Connect a serial adapter to UART-0 on the robostix and boot it up all by itself. The robostix will report what it sees on the i2c bus. You can press keys to modify what it does. 2 - Plug in the tweener to the robostix and see if the behaviour changes 3 - Run the gumstix with the wifistix. ssh in and run the i2c-test program. This might not work if you have an older gumstix (since the older gumstix doesn't have a pullup on the FFUART-RxD line). 4 - Plug in the tweener to the gumstix and see what happens when running i2c-test -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ |