naveen_pn@yahoo.com wrote:
> hi,
> I'm using a custom designed board having LH79520 with 32MB micron
> SDRAM & 8MB flash. Very similar to LogicPD board, but without the
> extras (lan, audio, CPLD, buffers etc). It does have a external reset
> chip.
> 
> The board works fine when no interrupts are used. However, when I try
> to use the timer interrupt, it works intermittently between power-ups.
> Meaning, the interrupt is working after a power-up on some occasions
> and doesn't on other occasions. But once the interrupt starts to work
> after a power-up, it will keep working until the next power cycle to
> the board. I've verified that the timer itself is configured properly
> and always counts, irrespective of whether interrupt is working or
> not.
> 
> I'm using standard Sharp ABL/CSP/BSP software package.
> 
> Please help!!
> 

We struggled with the same problem for months before a solution was found.
Sharp denied that there was a problem but eventually included the correct
wiring suggestion in the LH79525 manual.

The hardware people pointed at the software and the software people
pointed at the hardware. Eventually it was determined to be a hardware
issue.

 From the hardware designed who was able to find the solution:

<quote>
Early designs with the Sharp LH79520 had intermittent boot-up problems that
seemed to be related to power supply sequencing (3.3V and 1.8V).
We logically added the Reset signal to the TRST line in the JTAG input to
the CPU.
This trick was found in the errata for one of the newer members of the Sharp
processor family. We removed the various (unnecessary) delays in the power
supply enables of previous designs. We left the 100 Ohm resistive load on
the 1.8V supply to discharge the output capacitor when power was removed for a
short period of time.
<end quote>


Good Luck,
Dave

<naveen_pn@yahoo.com> wrote in message 
news:1181848375.905020.68910@a26g2000pre.googlegroups.com...
> hi,
> I'm using a custom designed board having LH79520 with 32MB micron
> SDRAM & 8MB flash. Very similar to LogicPD board, but without the
> extras (lan, audio, CPLD, buffers etc). It does have a external reset
> chip.
>
> The board works fine when no interrupts are used. However, when I try
> to use the timer interrupt, it works intermittently between power-ups.
> Meaning, the interrupt is working after a power-up on some occasions
> and doesn't on other occasions. But once the interrupt starts to work
> after a power-up, it will keep working until the next power cycle to
> the board. I've verified that the timer itself is configured properly
> and always counts, irrespective of whether interrupt is working or
> not.
>
> I'm using standard Sharp ABL/CSP/BSP software package.
>
> Please help!!
>
What do you mean by doesn't work?   Is it that the interrupt is never 
serviced, the code crashes to unknown locations, etc.  More detail is 
needed.
Does the code work on the LogicPD board, or are there differences that 
prevent the same code from working on both boards?

Scott 

hi,
I'm using a custom designed board having LH79520 with 32MB micron
SDRAM & 8MB flash. Very similar to LogicPD board, but without the
extras (lan, audio, CPLD, buffers etc). It does have a external reset
chip.

The board works fine when no interrupts are used. However, when I try
to use the timer interrupt, it works intermittently between power-ups.
Meaning, the interrupt is working after a power-up on some occasions
and doesn't on other occasions. But once the interrupt starts to work
after a power-up, it will keep working until the next power cycle to
the board. I've verified that the timer itself is configured properly
and always counts, irrespective of whether interrupt is working or
not.

I'm using standard Sharp ABL/CSP/BSP software package.

Please help!!