Freescale Semiconductor Microcontrollers User Manual
Page 443
HCS08 Full Chip Simulation
Peripheral Modules Commands
443
Microcontrollers Debugger Manual
Pulls up the data window with all the input values
>IICDI 22 33
This is an example of data being returned from a slave device. Once the MCU
transmits a start signal and the target address, it receives and ACK from the slave
device. An ACK is implied unless a NACK is specified via the IICDI command.
The next two data bytes read are 22 and 23. If the microprocessor attempts to read
another byte, it gets an $FF value followed by a NACK signal (NACK because
nothing remains in the input buffer). The receiving device then generates a STOP
signal. A more exact input from a device designed to return two bytes is:
>IICDI ACK 22 ACK 23 NACK
IIC in master mode transmits to a slave:
• If the slave device acknowledges all output bytes of the transmitting device,
there is no need to specify an input packet. If the master device is going to
transmit an address and two bytes, the following packet is equivalent to no
packet:
>IICDI ACK ACK ACK
• If, however, the slave receiver is designed to generate a NACK signal after the
second received data byte, the proper response packet is:
>IICDI ACK ACK NACK
• The address result being the first ACK, the first data result being the second
ACK, and the second data byte being the NACK.
IIC in MASTER mode is not acknowledged by any Slave:
>IICDI NACK
• If the NACK signal is entered before our master device transmits a START
signal, then the master device gets a NACK when it tries to read an
acknowledge after the address is output. The master device then generates a
STOP signal and releases the BUS.
IIC in SLAVE mode receives a Write from an external Master:
This example is for an external master which is writing to the microprocessor
configured to simulate the slave mode operation. The packet contains both START
and STOP signals which puts the simulated device into the slave mode.
>IICDI START 55 AA 22 STOP
This input adds five values to the input queue which is a packet from an external
master, including the following procedure values:
1. A start signal comes in
2. The address $55 comes, in specifying a write (slave receive). The Address
Register in the current simulated device has been previously set to $55