The following table contains known issues, scheduled bug fixes, and feature improvements for the Iris Carrier Board.
For other information, click on the below links:
Customer Impact: LVDS displays connected to the LVDS connector (X7) of the carrier board may not function (not show any picture and remain black) in case they require the HSYNC and VSYNC signals for synchronization. LVDS displays not requiring those signals are not impacted.
Description: Most LVDS displays don't rely on the HSYNC and VSYNC signals for synchronization, they use the data enable signal DE (LCD_BIAS) instead. However, there are some LVDS displays that require the HSYNC and VSYNC signals for proper operation. Unfortunately, it is oftentimes not clearly indicated in the displays' datasheets whether the HSYNC and VSYNC signals are required. In the Ixora V2.0, the HSYNC and VSYNC input signals of the TH63LVD827 bridge are swapped (the LCD_LCLK_A0 signal should be connected to the HSYNC input, and the LCD_FCLK_RD signal should be connected to the VSYNC input). As the LVDS link is transparent between the LVDS bridges (on the carrier board's and the display's side), the HSYNC and VSYNC signals are also swapped on the display's side.
Workaround: Use a display that does not require the HSYNC and VSYNC signals for synchronization. Check with your display manufacturer/supplier on the synchronization method used by the display.
Customer Impact: An assembly issue affecting an early production lot of the Iris V2.0A is causing a violation of a keepout zone defined for Colibri SoMs featuring an FFC connector on the bottom. These SoMs may not be properly inserted into the module connector of the affected carrier boards, potentially resulting in connection or reliability issues.
Description: An early production lot of the Iris V2.0A is affected by an assembly issue. The capacitor C133 assembled is violating a keepout zone defined for Colibri SoMs featuring an FFC connector on the bottom. These SoMs may not be properly inserted into the module connector of the affected carrier boards, potentially resulting in connection or reliability issues. Please check the related errata document for more information.
Workaround: Removal of the capacitor C133 fully resolves the issue. Carrier board functionality is not impacted by the modification. C133 is not assembled on later production lots of the Iris V2.0A.
Customer Impact: The RTC circuit of a small percentage of Iris V1.1A carrier boards shipped before the 30th of October 2015 has an abnormal current consumption. This causes the RTC battery to be depleted faster than expected.
Description: The issue affects about 4% of the Iris V1.1A carrier boards shipped before the 30th of October 2015 and is caused by a broken capacitor (C55). It is possible to check the RTC circuit current consumption by measuring the voltage across a shunt resistor connected in series with the power supply used to provide 3.3V on the battery holder positive pin. The normal RTC standby supply current should be around 1uA.
Workaround: Customers who received products before the 30th of October 2015 and use the RTC circuit should measure the current consumption on already received products. If an abnormal current consumption is detected, contact the Toradex RMA department to get the board fixed or replaced. Our testing process has been adjusted to find the mentioned problem and rework the affected products.
Customer Impact: With a single RS232 cable connected to the carrier board, there is a residual voltage of around 0.7V at the 3.3V rail. Besides the residual voltage, no negative impact has been detected/reported. No damage to the related module IO pins is expected.
Description: The RS232 port of the host computer is backfeeding to the Iris carrier board and the SoM through the RS232 transceiver. For example, in combination with the Colibri iMX6 module, a residual voltage of around 0.7V can be measured at the 3.3V rail while only the RS232 cable is connected to the carrier board.
Workaround: Consider replacing the RS232 transceiver (IC4 and/or IC6 on the Ixora) with a footprint-compatible part. Some of the alternative transceivers not prone to backfeeding: TI TRS3243EIDBR, TI MAX3243IDB, ST ST3243EBTR.
Customer Impact: With a single USB cable connected to the USB client port of the carrier board, there is a residual voltage of around 0.85V at the 3.3V rail of the SoM. Besides the residual voltage, no negative impact has been detected/reported. As the resistor R115 (560Ohm) limits the backfeeding current, no damage to the related module IO pin is expected.
Description: If the USB client cable is plugged in while all other power sources are removed, the voltage divider circuit (R115/R116) on the USB_C_DET signal is backfeeding the module. For example, in combination with the Colibri iMX6 module, a residual voltage of around 0.85V can be measured at the 3.3V rail.
Workaround: Increase the resistor value of the divider. Change the value of R115 to from 560R to 5.6k. Change the value of R116 from 1k to 10k. According to tests done with the Colibri iMX6, this reduces the residual voltage from 0.85V to 0.18V.
Customer Impact: When removing all of the other power sources while having a single USB cable connected to the USB client port, the carried board does not power down properly. The power rails continuously enable and disable, causing the blinking of the related power LEDs.
Description: If only the USB client cable is plugged in while all other power sources are removed, the USB power switching IC1 gets enabled and disabled periodically. The enable input of the power switch IC is active low. If the power rails are removed, the USB_P_EN signal goes slowly down, which at one point enables the USB power switch. This unintentionally powers the board from the USB source through the 5V buck converter and turns on the 3.3V buck regulator. Since the 3.3V rail is up, the USB_P_EN signal also goes high and disables the USB power switch. This cycle repeats continuously and makes the power LEDs blinking.
Workaround: Remove the resistor R156 and assemble the resistor R157 instead. This prevents the continuous power cycles from starting since the USB power switch and the buck converters remain powered down. The backfeeding protection circuit inside the USB power switch (IC1) works and disables the switch regardless of the USB_P_EN signal level.
