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Preliminary Information | MT90840 |
Internal Memory Description
Transmit Path Connection Memory High (TPCM High) - This is an
OE/ | PPBY | MC | CTo1 | CTo2/ | CTo3/ | AB9 | AB8 | |
CTo0 | AB11 | AB10 | ||||||
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7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
(TX Path CM High)
OE/CTo0 Output Enable. Provides per channel tristate control on the parallel port side. It controls the MT90840 parallel output drivers to disable (tristate, when LOW) or enable (when HIGH) the transmission of data from the device. The contents of this bit will also be clocked out on the CTo0 output pin at the parallel port rate.
PPBY Parallel Port Bypass Enable. Indicates that the parallel output channel is going to contain bypassed (PPBY=HIGH) data from the Receive parallel port of the MT90840. The channels that are not bypassed (PPBY=LOW) can be used for switching of data from the serial port side, or for
MC Message Channel. The message channel contents are programmed by the CPU into the TP Connection Memory Low. If MC=1 the contents of the corresponding location of TPCM Low are output on the corresponding channel at the Transmit parallel port. If MC=LOW, the contents of the programmed location in TPCM Low act as an address for the Data Memory, and so determine the source channel for this output channel. Depending on the timing mode selected, the source of the connection can be an input channel from either serial (TM1, 2, or 3) or parallel (TM4) data ports. This bit overrides PPBY if both are set HIGH.
Transmit Path Connection Memory Low (TPCM Low) - This is an
AB7 | AB6 | AB5 | AB4 | AB3 | AB2 | AB1 | AB0 |
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7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
(TX Path CM Low)
In Timing Mode 4, these 8 bits are used along with bits
If message mode is selected at TPCM High bits, the contents of the
USE OF THE TPCM HIGH AND LOW ADDRESS BITS WHEN SELECTING SOURCE
SERIAL STREAM and CHANNEL ALLOCATION | SOURCE STREAM ADDRESSING | SOURCE CHANNEL ADDRESSING | |||
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2 Mbps | 16 i/o (512 channels) | AB5,AB6,AB7,AB8 (up to 16 streams) | AB0 to AB4 used to select up to 32 channels | ||
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4 Mbps | 8i x 8o (512 channels) | AB6, AB7, AB8 used to select up to 8 | AB0 to AB5 used to select up to 64 channels | ||
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8 Mbps | 4i x 4o (512 channels) | AB7, AB8 used to select up to 4 streams | AB0 to AB6 used to select up to 128 | ||
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SOURCE CHANNEL ADDRESSING IN TM4 |
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6.48 Mbyte/s |
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16.384 Mbyte/s |
| AB0 - AB10 (one of 2048 input channels) |
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19.44 Mbyte/s |
| AB0 - AB11 (one of 2430 input channels) |
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