8XC196Kx, Jx, CA USER’S MANUAL

9.3HARDWARE CONNECTIONS

Figure 9-3 shows the basic hardware connections for both multiplexed and demultiplexed bus modes. Table 9-3 lists the interconnections. Note that the shared memory mode (8XC196KS and KT only) supports only a multiplexed bus, while the standard slave mode supports either a multiplexed or a demultiplexed bus.

Table 9-3. Master and Slave Interconnections

When using a multiplexed bus, connect the master’s AD1 pin to the slave’s SLP1 pin and the master’s ALE pin to the slave’s P5.0 pin. When using a demultiplexed bus, connect the master’s address output (A1) to the slave’s SLPALE (P5.0) pin. The master’s AD1 (with a multiplexed bus) or A1 (with a demultiplexed bus) signal must be held high to either write to the slave’s command register (SLP_CMD) or read the slave’s status register (SLP_STAT). It must be held low to either write to the slave’s P3_PIN register or read the slave’s P3_REG register.

The configurations shown in Figure 9-3 allow the master to select the slave device by forcing SLPCS# low. The master can then request that the slave perform a read or a write operation by forcing SLPRD# or SLPWR# low, respectively. Data is latched on the rising edge of either SLPRD# or SLPWR#. When the slave completes a read or a write, it notifies the master via the SLPINT signal.

When the master writes to the P3_PIN register, the input buffer empty (IBE) flag is cleared and SLPINT is pulled low. When the slave reads P3_PIN, the IBE flag is set and SLPINT is forced high. This notifies the master that the write operation is completed and another write can be performed.

When the slave writes to P3_REG, the output buffer full (OBF) flag is set and SLPINT is forced high. This notifies the master that P3_REG contains valid data from the previous read cycle. Note that this is a pipelined read. The address specified in the previous read cycle is fetched and placed into the P3_REG register to be read by the master in the next read cycle. When the master reads from P3_REG, the OBF flag is cleared and SLPINT is pulled low.

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