DB839 Datasheet, PDF (13/20 Pages) CML Microcircuits – Two Variable Attenuators

Digitally Controlled Analog I/O Processor
13
MX839 PRELIMINARY INFORMATION
4.8 Read Only Register Description
4.8.1 IRQ FLAGS Register (Hex Address $D1)
HIRQF1 (Bit 1)
HIRQF2 (Bit 3)
HIRQF3 (Bit 5)
HIRQF4 (Bit 7)
LIRQF1 (Bit 0)
LIRQF2 (Bit 2)
LIRQF3 (Bit 4)
LIRQF4 (Bit 6)
These bits are set if the relevant digital magnitude comparator input exceeds its upper reference level.
These bits are reset to '0' immediately after reading the IRQ FLAGS register. When any of these bits
are set, an interrupt will be generated if the relevant reference level is not zero.
These bits are set if the relevant digital magnitude comparator input falls below its lower reference
level. These bits are reset to '0' immediately after reading the IRQ FLAGS register. When any of
these bits are set, an interrupt will be generated if the relevant reference level is not zero.
Table 9: IRQ FLAGS Register (Hex Address $D1)
4.8.2 A/D DATA1 Register (Hex Address $DC)
4.8.3 A/D DATA2 Register (Hex Address $DD)
4.8.4 A/D DATA3 Register (Hex Address $DE)
4.8.5 A/D DATA4 Register (Hex Address $DF)
This data will consist of two bytes each. Bit 7 to Bit 2 of the second data byte will be set to '0'. Bits 0-7 of the first byte are
the lease significant 8 bits while Bits 0-1 of the second byte are the most significant 2 bits of the 10 bit conversion.
The analog input (V_IN) is converted to a 10-bit digital word (w) according to:
w = ^VIN ×1024
AV_DD
The bits of word (w) are returned in 2 bytes as follows:
7654321 0
Return Byte 1 w₇ w₆ w₅ w₄ w₃ w₂ w₁ w₀
Return Byte 2 0 0 0 0 0 0 w₉ w₈
5 Application
5.1 C-Bus Clock
Although this is specified as a 500kHz clock for compatibility with other C-BUS devices, the MX839 C-BUS will operate
over a much wider range. Users should ensure that the C-BUS clock is at least 4 times slower than the crystal or external
clock on Pin 2 of the MX839.
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