Rabbit OP7100 User Manual download pdf (Page 48)

42 eDisplay (OP7200)

3.9 OP7200 CPLD

All the random logic used to control the OP7200 is contained within a single ComPlex

Logic Device (CPLD). The AMD ATF1500A contains 32 macrocells and is packaged in a

44-pin TQFP. This device contains decoding and a number of I/O bits that can be set to

high or low to control various functions of the OP7200.

The CPLD interfaces to the address and data bus on the RabbitCore module, and is write-

only. Two chip select lines, /PE4 and /PE5, are used to enable the device. /PE4 and /PE5

are configured in software as I/O strobes, and set the base address used by the CPLD. /PE4

is used when selecting one of the sixteen I/O control bits associated with the eight driver

circuits. /PE5 is used with the remainder of the controls. The control bits within the CPLD

normally can be set and reset independently of one another. The SINK and SOURCE out-

puts are different in that both the SINK and SOURCE outputs for a particular driver can-

not be asserted simultaneously. If either the SINK or SOURCE output is asserted, and the

software tries to set the other, the operation is ignored and the bit will not be set. The pur-

pose of this interlock is to prevent damage to the driver circuit by not allowing both cur-

rent sourcing and sinking to be enabled simultaneously.

Table 6. CPLD Parameters

/PE5 /PE4 A3–0 D0 Signal Function

1 0 0000 1 SINK0 Enable Sink Output 0

1 0 0000 0 SINK0 Disable Sink Output 0

1 0 0001 1 SINK1 Enable Sink Output 1

1 0 0001 0 SINK1 Disable Sink Output1

1 0 0010 1 SINK2 Enable Sink Output 2

1 0 0010 0 SINK2 Disable Sink Output 2

1 0 0011 1 SINK3 Enable Sink Output 3

1 0 0011 0 SINK3 Disable Sink Output 3

1 0 0100 1 SINK4 Enable Sink Output 4

1 0 0100 0 SINK4 Disable Sink Output 4

1 0 0101 1 SINK5 Enable Sink Output 5

1 0 0101 0 SINK5 Disable Sink Output 5

1 0 0110 1 SINK6 Enable Sink Output 6

1 0 0110 0 SINK6 Disable Sink Output 6

1 0 0111 1 SINK7 Enable Sink Output 7

1 0 0111 0 SINK7 Disable Sink Output 7

1 0 1000 1 SOURCE0 Enable Source Output 0

1 0 1000 0 SOURCE0 Disable Source Output 0

1 0 1001 1 SOURCE1 Enable Source Output 1

1 0 1001 0 SOURCE1 Disable Source Output 1

1 0 1010 1 SOURCE2 Enable Source Output 2

1 0 1010 0 SOURCE2 Disable Source Output 2

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Rabbit OP7100 User Manual Page 48