From: Paul N. 2 <idr...@gm...> - 2011-10-16 09:36:58
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I`ve spent over a year developing a GumStix based product. All I have to show for it is this: http://idruna.com/images/overo/Overos.JPG All of them died within 4 seconds to 4 days of being plugged into my custom board. When plugged into the Summit as a reference, with a working MicroSD card, the green power light comes on, but the blue light does not. No text on the terminal. The latest deaths have all been Sands, so no NAND. My designer, who has successfully produced similar boards in the past, has gone over my boards with a fine tooth comb and oscilloscope, and every single pin is within the GumStix specifications. I hired a 2nd highly experienced engineer to go over the board and he doesn't see anything that could kill an Overo either. The boards were professionally made and assembled by Sierra Circuits. Here is a link to the pins connected to the Overo: http://idruna.com/images/overo/OveroPins.JPG Our first thought was that USBH_VBUS was the problem. That line has since been cut, it doesn't appear to be needed. Our second thought, if unlikely, was that R9 and R13 should be changed to 1.8K to get the voltage at exactly 1.8V instead of 2.0V. No luck. Our third thought was confirmed by Don to be an Overo killer, and that was the 3.3V supply coming on for a short time when power is first applied before being turned off by the PIC. As there is no documentation on the minimum length of time the Overo must be powered on before it can be powered down, I changed the PIC firmware to simply leave 3.3V on at startup to eliminate this as a potential problem. Another day, another dead Overo. ADCIN2, OTG_VBUS, PWM1, PWM0, OTG_N, OTG_P, GPIO71, GPIO 70, GPIO 72, OLED_RES, OV_SDA, OV_SCL, OLED_DC go to headers or connectors that are not connected to anything at this stage. That leaves the following pins as the only ones connected: GND VSYSTEM - looks perfect on the scope. Supplied by an LT3971-3.3, connected to two protected 18650 batteries (7.2-8.4V). N_MANUAL_RESET - connected to PIC32 via resistor VBACKUP - connected to the PIC32's power supply GPIO166_IR_TXD3 - connected to a PIC32 via level shifter GPIO165_IR_RXD3 -- connected to a PIC32 via resistor GPIO148_TXD1 -- connected to a PIC32 via level shifter GPIO151_RXD1 -- connected to a PIC32 via resistor GPIO173_SPI1_MISO - connected to ADS7846IRGVR touch controller via level shifter GPIO172_SPI1_MOSI - same GPIO12_MMC3_CLK - same GPIO175_SPI1_CS1 - same GPIO114_SPI1_NIR Q- same USBH_DP - connected to USB2517 7 port hub USBH_DM - same Can anyone think of any possible way I could be killing all these Overos? Thanks, -- Paul Nolan, CEO Idruna Software Inc. -- View this message in context: http://old.nabble.com/How-have-I-managed-to-kill-10-Overos--tp32660989p32660989.html Sent from the Gumstix mailing list archive at Nabble.com. |