user/imxrt: Add notes about problems with EVB

There are some possible problems with the i.MXRT1050 evaluation board.
Make some notes about that in the BSP manual.

1 files changed, 9 insertions, 0 deletions

diff --git a/user/bsps/arm/imxrt.rst b/user/bsps/arm/imxrt.rst
index 3f8b270..f8d9731 100644
--- a/user/bsps/arm/imxrt.rst
+++ b/user/bsps/arm/imxrt.rst
@@ -10,6 +10,10 @@ This BSP offers only one variant, the `imxrt1052`. This variant supports the
 i.MXRT 1052 processor on a IMXRT1050-EVKB (tested with rev A1). You can also
 configure it to work with custom boards.
 
+NOTE: The IMXRT1050-EVKB has an backlight controller that must not be enabled
+without load. Make sure to either attach a load, disable it by software or
+disable it by removing the 0-Ohm resistor on it's input.
+
 Build Configuration Options
 ---------------------------
 
@@ -41,6 +45,11 @@ Then just copy the generated binary to the mass storage provided by the
 debugger. Wait a bit till the mass storage vanishes and re-appears. After that,
 reset the board and the newly programmed application will start.
 
+NOTE: It seems that there is a bug on at least some of the on board debuggers.
+They can't write more than 1MB to the HyperFlash. If your application is bigger
+than that (like quite some of the applications in libbsd), you should use an
+external debugger or find some alternative programming method.
+
 For debugging: Create a special application with a `while(true)` loop at end of
 `bsp_start_hook_1`. Load that application into flash. Then remove the loop
 again, build your BSP for SDRAM and use a debugger to load the application into