AGFA Avantra 36/44 Service Manual page 95

Avantra 36/44 Service Manual
3.2.3.14 DEC Micro-controller Test Descriptions
The following list describes the tests performed on the DEC micro-controller during
the boot sequence.
• Internal ROM Checksum– performs a rotate and add checksum. Bytes
are added to a 16-bit sum, after the sum has been rotated right one posi-
tion. Bit 0 is rotated into bit 15. The resulting checksum is compared to
the checksum stored in ROM.
• DEC Offgate Register Test– writes a three byte sequence, where the first
three bytes represent the test data and the last three bytes are a sequence
of zeros used to retrieve the previous three bytes written. As the data is
read back, it gets shifted left by 5.
• DEC Ongate Register Test– writes a 6-byte sequence, where the first
three bytes represent the test data and the last three bytes are a sequence
of zeros used to retrieve the previous three bytes written. As the data is
read back, it gets shifted left by 5.
• DEC Vacuum Register Test– writes a 2-byte pattern into the vacuum regis-
ter. The first byte is the real data and the second byte is used to retrieve
the feedback.
• DEC to DSP SPI Link Test– the Echo command verifies the SPI link to the
DSP from the DEC. The K-4 sends an SPI echo command packet (3F 0 55
AA), which tells the DSP to echo the received packet. The K-4 sends
another echo packet (3F 0 0 0) to the DSP, which reads back the contents
of the first echo packet. The data read back is compared to the expected
data pattern. If the comparison fails, an error is returned, otherwise the test
returns a pass.
• Carriage Test– moves the carriage forward 1/16¨ to verify that the DEC-K4
receives the carriage encoder signal. As the carriage moves, the DSP
checks for a wall condition. If a wall is detected in the forward direction,
then a short move in the reverse direction is tried.
3-8 Diagnostics