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Colibri PXA270 V2.4C RAM Drive Strength Settings

 
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Summary

The RAM drive strength settings configured in Windows CE bootloader versions V4.1, V4.2, andV4.3 could lead to single bit RAM errors on the Colibri PXA270 V2.4C modules. Older versions of the bootloader are not affected by this problem as they already use the drive strength settings as required by the new module versions.

Affected Products

Product NumberProduct Name
00082402Colibri PXA270 312MHz V2.4C
00092402Colibri PXA270 520MHz V2.4C
No other hardware versions are affected.

Description

During extensive burn-in tests on a particular combination of hardware and software revisions we identified stability issues. At elevated temperatures, single bit RAM errors occurred when running Eboot V4.1, V4.2, or V4.3 on Colibri PXA270 V2.4C.

Detailed Information

In the critical Eboot revisions, the signal drive strength configured for the RAM signal CLK1 could cause bit errors in the communication between CPU and RAM. The following drive strength register settings solve the problem:

Module Version BSCNTR0 value (addr: 0x4800004C)
V1.0A to V1.2F 0xFF1FFFFF
V1.2G to V2.4B 0xFFFFFFFF
V2.4C 0xFF1FFFFF

Solutions for WinCE

Solution 1: Use Newer Bootloader (preferred)

Use the Windows CE bootloader Eboot V4.4 or newer which sets an optimized drive strength automatically. This is the preferred solution. Note: The bootloader V4.4 isn't available yet but will be available before shipping V2.4C modules.

Solution 2: Use Older Bootloader

Continue to use an older bootloader and set the active drive strength in the bootloader configuration block. You can use the ColibriPXA270FixMBS_V2.0 tool or you can set it manually through the bootloader menu.

Use the ColibriPXA270FixMBS_V2.0 Tool

You can use the ColibriPXA270FixMBS_V2.0 tool which was developed to fix the issue described on this page. The tool evaluates the module HW version and changes the drive strength setting in the config block only if required. Therefore it's safe to run this tool on any Colibri module HW and BSP version. The changes are stored to the config block and also directly applied to the running system. A reboot isn't necessary. You can use the AutoRun feature of the Toradex Windows CE images to automatically execute this tool when attaching any mass storage device like USB Memory Stick, SD Card, etc. Just create a folder called AutoRun in the root directory of the storage device and copy the desired tool into this folder.

There are two versions of this tool in the zip file below

  • ColibriPXA270FixMBS_V2.0.exe
    shows a message box about the modification
  • ColibriPXA270FixMBS_V2.0_unattended.exe
    runs quietly without any message

Manually change the Configuration in the Config Block

You can edit the config block through the bootloader menu's command prompt or by using the latest config block editor tool (V0.6 or newer). The following example shows the commands in the command prompt mode of the bootloader:

Used Commands:
SPACE             // to enter bootloader menu
x                 // to enter command prompt mode
set mbs.clk1=1    // to set the new drive strength value
save mbs          // to save the change to flash
Perform a reboot to apply the settings

The bootloader output should look like this when using the commands above:
Toradex Bootloader 4.1 for Colibri Built Sep 14 2012

Press [SPACE] to enter Bootloader Menu

BootLoader Configuration:

C) Clear Flash Registry
X) Enter CommandPrompt Mode
D) Download image to RAM now
F) Download image to FLASH now
L) Launch existing flash resident image now

Enter your selection: x
>set mbs.clk1=1
>save mbs
>

Solution for Linux

Please refer to the register settings explained in the section Detailed Information above.