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Why initial operation is not working correctly even the board has made?

Latest Updated:03/26/2009

Question:

The board has been made, but initial operation is not working correctly. What items should be checked?

Answer:

Please check the following:

1) Is each power supply supplied correctly?

2) Is the correct potential applied?

3) Are clocks input to SH-3?

4) Are the conditions and timing of the power-on reset correct?

5) SH-3 is not initialized by a manual reset.

A power-on reset must always be performed when powering on.

6) Is the SH7705 MD6 connected (or pulled down) to VssQ?

7) Is MODE<5:0> fixed to each setting level ('High' or 'low')?

8) Does CKIO output expected frequency?

9) Is access to Area0 performed after releasing a power-on reset

(SH-3 accesses to h'a000 0000 when a power-on reset is released.)

10) Is /WAIT negated "High"?

11) CA pin (CA pin must be pulled up externally when hardware standby is not used.)

12) ASEMD0 setting. ASEMD0 must be high when the emulator or H-UDI are not used.

13) Please refer to the following FAQ about SH7705 TRST pin.

Can SH7705 TRST pin (142-pin) be pulled down at 1k-ohm? (In normal operation)

14)Please check the status of STATUS[1:0] pin before and after a reset.

STATUS[1:0]=HH: Reset, STATUS[1:0]=LL: Normal operation

Suitable Products
SH7729R
SH7727
SH7720
SH7709S
SH7706
SH7705