Intel 8XC196MD, 8XC196MH, 8XC196MC manual Bidirectional Port Considerations, HZ1

8XC196MC, MD, MH USER’S MANUAL

Table 6-10. Port Pin States After Reset and After Example Code Execution

Action or Code			Resulting Pin States†
	Px.7 Px.6		Px.5	Px.4 Px.3		Px.2	Px.1 Px.0
Reset	wk1	wk1	wk1	wk1	wk1	wk1	wk1	wk1
LDB Px_DIR, #00011111B	1	1	1	wk1	wk1	wk1	wk1	wk1
LDB Px_MODE, #00000000B	1	1	1	HZ1	HZ1	HZ1	HZ1	HZ1
LDB Px_REG, #10010011B	1	0	0	HZ1	0	0	HZ1	HZ1

†wk1 = weakly pulled high, HZ1 = high impedance (actually a “1” with an external pull-up).

6.3.4Bidirectional Port Considerations

This section outlines special considerations for using the pins of these ports.

Port 1 (8XC196MH)	After reset, your software must configure the device to match the
	external system. This is accomplished by writing appropriate config-
	uration data into P1_MODE. Writing to P1_MODE not only
	configures the pins but also turns off the transistor that weakly holds
	the pins high (Q4 in Figure 6-2 on page 6-8). For this reason, even if
	port 1 is to be used as it is configured at reset, you should still write
	data into P1_MODE.
Port 2	After reset, your software must configure the device to match the
	external system. This is accomplished by writing appropriate config-
	uration data into P2_MODE. Writing to P2_MODE not only
	configures the pins but also turns off the transistor that weakly holds
	the pins high (Q4 in Figure 6-2 on page 6-8). For this reason, even if
	port 2 is to be used as it is configured at reset, you should still write
	data into P2_MODE.
P2.7	A value written to P2_REG.7 is held in a buffer until P2_MODE.7 is
	cleared, at which time the value is loaded into P2_REG.7. A value
	read from P2_REG.7 is the value currently in the register, not the
	value in the buffer. Therefore, any change to P2_REG.7 can be read
	only after P2_MODE.7 is cleared.
Port 5	After reset, the device configures port 5 to match the external system.
	The following paragraphs describe the states of the port 5 pins after
	reset and until your software writes to the P5_MODE register.
	Writing to P5_MODE not only configures the pins but also turns off
	the transistor that weakly holds the pins high (Q4 in Figure 6-2 on
	page 6-8). For this reason, even if port 5 is to be used as it is
	configured at reset, you should still write data into P5_MODE.
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