78M6612 Data Sheet
Table 39:
DIO_DIR
Control Bit
DIO_DIR [n]
0
DIO Pin n Function
Input
1
Output
DS_6612_001
Additionally, if DIO6 and DIO7 are declared outputs, they can be configured as dedicated pulse outputs
(WPULSE = DIO6, VARPULSE = DIO7) using
DIO_PW
and
DIO_PV
registers. In this case, DIO6 and
DIO7 are under CE control. DIO4 and DIO5 can be configured to implement the EEPROM Interface.
If the optical UART is not used, TX1 and RX1 can be configured as dedicated DIO pins (DIO1, DIO2,
see
A 3-bit configuration word, I/O RAM register,
DIO_Rx
(0x2009[2:0] through 0x200E[6:4]) can be used for
certain pins, when configured as DIO, to individually assign an internal resource such as an interrupt or a
timer control (see
for DIO pins available for this option). This way, DIO pins can be tracked
even if they are configured as outputs.
Tracking DIO pins configured as outputs is useful for pulse counting without external
hardware.
When driving LEDs, relay coils etc., the DIO pins should sink the current into ground (as
shown in
, right), not source it from V3P3D (as shown in
, left). This is
due to the resistance of the internal switch that connects V3P3D to either V3P3SYS or
VBAT.
When configured as inputs, the dual-function (DIO/SEG) pins should not be pulled above
V3P3SYS in MISSION and above VBAT in LCD and BROWNOUT modes. Doing so will
distort the LCD waveforms of the other pins. This limitation applies to any pin that can be
configured as a LCD driver.
The control resources selectable for the DIO pins are listed in
If more than one input is
connected to the same resource, the resources are combined using a logical OR.
78M6612
78M6612
V3P3SYS
VBAT
V3P3D
DIO1
3.3V
V3P3SYS
VBAT
V3P3D
DIO1
3.3V
LED
R
LED
DGND
Not recommended
DGND
R
Recommended
Figure 8: Connecting an External Load to DIO Pins
44
Rev. 1.2
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
