StrongARM 110 Evaluation Board FAQ

Rear view of the SA 110 Evaluation Board
  1. The serial console produces a few lines of unreadable output on reset before the proper boot text appears.
  2. All serial console output is unreadable
  3. An ATX power supply is attached but the system will not power up.
  4. An ATX power supply is attached but the system is not stable or measured supply voltages are wrong.
  5. What is the default serial settings used by the bootloader on this board?
  6. After an upgrade to 256MB memory the system no longer starts.
  7. What is the maximum amount of memory this board can have fitted?
  8. Are there any special requirements for the memory used?
  9. When choosing a 256MB DIMM module what are the selection criteria?
  10. How are the parameters in question 9 arrived at?
  11. What 256MB modules have been reported to work?

  1. The serial console produces a few lines of unreadable output on reset before the proper boot text appears.

    The baud rate divisors for the serial system are derived from the systems memory clock (fclk) this clock may be set to one of four possible speeds (50,55,60 and 66MHz).

    This value is computed by ABLE early in the boot sequence, unfortunately some useful output is generated from the DRAM probe before this value can be computed. The default serial baud rate is set assuming an fclk of 50MHz. If the board is setup with one of the other options the early diagnostic values are output at a non standard baud rate which produces the unreadable output

  2. All serial console output is unreadableThis is generally caused by the main memory clock being set to a value other than 50MHz and using a version of ABLE older than 1.79. The system should be configured to use a 50MHz memory clock (using links LK4 and LK5 and the white text box near the jumpers as reference). The system may then be upgraded to ABLE 1.79 or later and the memory clock reset to the desired value.
  3. An ATX power supply is attached but the system will not power up.This is an increasingly common issue with modern ATX power supplies. It is usually caused by the small amount of power drawn by the system. A base board with memory and network card installed uses around 5W. Even with a hard disc attached, this may not be enough to reach the supply's required minimum current draw. The larger the supply the larger the required minimum power use. Typically, a 250W supply will require a minimum power usage of 10W to turn on and beome stable, whereas a 400W supply may well require 20W, or more, to start. A system with no hard disc attached may well struggle to reach the minumum requirements of a 250W supply and, almost certainly, will not operate with a 400W supply.

    The only solution to this issue is to purchase the smallest rated supply possible and check it has a low minimum power rating.

  4. An ATX power supply is attached but the system is not stable or measured supply voltages are wrong. This typicaly means the board and peripherals are not using enough power to keep the supply stable and the supply does not have internal sense to shutdown. This is a similar issue to Q3 but may also have the addition issue that the system may need to draw enough power from a specific voltage rail from which the PSU derives all its other voltages e.g. the system may be drawing 100W from the 5V and 3.3V lines but little from the 12V line and still be unstable if the PSU regulates from the 12V line.

    The only solution is either draw more power from the correct voltage lines or replace the PSU.

  5. What is the default serial settings used by the bootloader on this board?The default serial speed for this board is 38,400 baud eight data bits, no parity and one stop bit. Hardware flow control should be disabled.
  6. After an upgrade to 256MB memory the system no longer starts.ABLE versions prior to 1.80 do not support this memory configuration. upgrading to ABLE 1.80 or later fixes this issue.
  7. What is the maximum amount of memory this board can have fitted?The maximum amount of memory this board can accept is 256MB in a single DIMM module (in slot 0)
  8. Are there any special requirements for the memory used?

    Almost any 168pin non parity DIMM module rated for 66MHz (PC66 or better) will work in this board, however the footbridge (northbridge) only supports a limited memory shape which may cause some of the fitted RAM not to be available with some modules.

  9. When choosing a 256MB DIMM module what are the selection criteria?

    Because the footbrige only allows for a limited memory shape any selected module must conform to certian parameters or some of the memory will simply not be available

    The memory "shape" is defined by several factors:

    • Row Address Select (RAS) maximum width is 12 bits (4096)
    • Column Address Select (CAS) maximum width is 10bits (1024)
    • Four Chip Select (CS) lines (top two routed to bank 0 only)
    • The data width of the physical chips which make up the module either eight or sixteen bits.
    • The number of devices used.

    In practice this reduces the choice to a single double sided DIMM module (because only these modules typicaly use all four chip selects, two for each side) in bank 0 (only this slot has all four CS lines wired) with either sixteen eight bit wide chips or eight sixteen bit wide chips. Care must be taken to ensure the maximim CAS and RAS parameters are not exceeded.

  10. How are the parameters in question 9 arrived at?

    This is calculated by using:
    size = CAS width x RAS width x CS count x chip width x chip count
    Maximum CAS by RAS size is 4096 x 1024 = 4194304
    Maximum number of chip selects is 4
    Overall Size (in bits) needed is 2147483648 This gives :
    chip width x chip count = 2147483648 / (4194304 x 4)
    chip width x chip count = 128
    This has the two possible soultions outlined of eight bits by sixteen chips or sixteen bits in eight chips.

  11. What 256MB modules have been reported to work?Some modules that have been reported as working are
    • Micron MT16LSDT3264A This is sold rebranded by Crucial (Crucial have been helpful in ensuring the correct modules are supplied, ensure you make your needs known before you order)
    • Kingston KVR133X64C3Q/256 DIMM

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