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TA Card Errata Thread 
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This thread exists to document known issues with past and possibly present TA cards. Your card could be from any era and have or not have any of these faults. If they don't affect you, don't "fix" them (if it ain't broke, don't fix it). But it is worth reviewing this to ensure that they aren't affecting you in some subtle way.

One post per item to keep it nice and clear.

Listing of possible issues:

  • Regulator under sized and over heating
  • PLL values looser than recommended
  • Clock control pin pulled to 2.5V instead of ground
  • ADC V ref buffered with 1k resistor causing bad readings
  • Heartbeat LED on PA6
  • Use of headers to supply 5V power

Comments here: viewtopic.php?f=62&t=1316

Fred.

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Tue Sep 20, 2011 10:33 pm
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On older TA cards a low performance regulator was supplied that only produced up to 100mA, current models carry an LM2937 LDO unit good for 500mA. Check yours to see what you have before modifying it.

In all cases, if drawing significant current and/or using a relatively high input voltage (12+) then your regulator will need a heat sink.

Pics and further instructions to come.

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Tue Sep 20, 2011 10:35 pm
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On most TA cards the PLL values used are as follows:

3.3nf 330pF and 3.9k

These seem to work fine, but aren't optimal according to Freescale or my calculations. If you experience clock issues, consider upgrading them to one of the following combinations:

  • 3.3k, 6.8nF and 680pF (critically damped) Fred's arbitrary recommendation
  • 3.9k, 6.8nF and 680pF (compromise for common values) Closest to TA values but with tighter damping
  • 4.7k, 4.7nF and 470pF (compromise for common values) Freescale's recommendation

EDIT: Reference to original post on this: viewtopic.php?p=17724#p17724

And document reference: A.5.3.1 for the math.

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Tue Sep 20, 2011 10:39 pm
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On most TA cards there is an error with the configuration of the crystal control pin. This pin should be pulled to 5v, and has an internal pull up to do this during RESET. The jumper JB2 should be cut or removed. Both resistors can stay in place, though R22 is redundant (still a good thing to have, however) and R16 is counter productive when JB2 is installed.

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Tue Sep 20, 2011 10:43 pm
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On all TA cards to the current time, R5 connects the MCU analogue module reference pin to the 5V supply. R5 has a value of 1k and at the 3mA that I measured or the 2.5 or 5mA that Freescale spec, drops a significant voltage (0.25 - 0.5V) and skews ADC readings by around 10% or so. This resistor should be bridged to avoid this problem and produce accurate ADC readings.

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Tue Sep 20, 2011 10:46 pm
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As of commit 45c38682f492a28315f81ab6ce7b909eec4e22bb PA6 is now used as a full time diagnostics output. For the time being, all it does is flash on 1 second off 1 second at 0.5Hz. In future it will be more useful, though it's still nice to see that the firmware is alive and running properly after a fresh code load.

If you want to see this signal for peace of mind, then you need to add a few components (2 or 3). Due to the way the switch is setup on the TA card, you can't go too low in resistance for the LED limit resistor. I used 2.7k and paralleled a 10k around both the LED and the 2.7k resistor in preparation for future SM code variants which will not have a pull up enabled on PORTA. By default the PORTA pins will be pulled up by the SM, however if you wish to run injectors or coils from PORTA using Sean's XG BB code in future then you will need the 10k too.

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Fri Jan 27, 2012 4:07 pm
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You shouldn't use the headers to supply 5V power to the board. The traces from/to them are very thin and not well routed for power purposes. On the other hand, the traces from the 2 pin power header are good enough. Thus once you have removed/bridged your regulator and plugged in your board, solder your power wires to those pins or pads for maximum reliability. There have been several instances of people trying to feed power up through the headers, and it only causes issues. Avoid doing that!

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Thu Sep 12, 2013 2:26 pm
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