8 Contact Check
Stable operation cannot be expected when the connection between a device and IC socket
is poor for parallel programming.
Probability of fail-to-make of the connection for parallel programming may be higher than
serial programming since more pins are used for parallel programming.
The MFW1U has adopted the contact check function for parallel programming in order to
avoid a fail-to-make-connection.
Contact check is achieved by the following 2 steps described below:
(1) Short check for the signal pins of a device and the GND pins.
(Checking is achieved to the entire devices at the same time.)
(2) Contact check for the device pins and the IC socket pins.
(Checking is achieved to each device.)
Further operation is interrupted and both of the PASS/FAIL LEDs are to be on to a
troubled adapter when a contact error is detected by either of the above step (1) or (2).
NOTE: PASS/FAIL LEDs of all the adapters are to be on since a troubled device cannot be
identified when an error is detected by the step (1).
The following error causes are considered for a contact error. Release the probable error
causes and retry the operation.
(1) The device is placed improperly such as up-side-down, wrong side, or deviation.
(2) Fail-to-make-connection is occurred since the pin of the IC socket or device is bent.
(3) Defective of the device.
Note that the following exceptions are examined.
(1) Fail-to-make-connection of the Vcc pin: Both of the PASS/FAIL LEDs are off since
the MFW1U judges no device is placed at the IC socket.
(2) Contact check is not available to the mode set pins and other pins, and so the only
FAIL LED is on even if the trouble is actually the contact error.
(3) When the device pin is bent and contacted to the Vcc pin or the “H” level fixed pin
(that is connected to the Vcc through resistance), the result of a contact check of a
troubled device is PASS and other effective device(s) is/are FAIL.
This kind of device pin bent tends to be occurred at corner pins.
Therefore, inspecting corner pins of a passing device is fully recommended.
NOTE: The contact point of the IC socket gets dirty and fail-to-make-connection may be
occurred during operation. Clean the contact point with a brush sometimes.
Multifunctional Flash Microcomputer [S550-MFW1U]
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Operation Manual
