71M6521FE-IMSLASHF datasheet(41/107 Pages) MAXIM

41 / 107 page

71M6521DE/DH/FE Data Sheet

Rev 2

Page: 41 of 107

DIO

Pin no. (64 LQFP)

Pin no. (68 QFN)

Data Register

DIO0=P0 (SFR 0x80)

DIO1=P1 (SFR 0x90)

Direction Register

DIO_DIR0 (SFR 0xA2)

DIO_DIR1 (SFR 0x91)

Internal Resources

Configurable

DIO

Pin no. (64 LQFP)

Pin no. (68 QFN)

Data Register

DIO2=P2 (SFR 0xA0)

Direction Register

DIO_DIR2 (SFR 0xA1)

Internal Resources

Configurable

Table 54: Data/Direction Registers and Internal Resources for DIO Pin Groups

DIO_DIR [n]

DIO Pin n Function

Input

Output

Table 55: DIO_DIR Control Bit

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.

The PB pin is a dedicated digital input. If the optical UART is not used, OPT_TX and OPT_RX can be configured as

dedicated DIO pins (DIO1, DIO2, see Optical Interface section).

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 Table

54 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 GNDD (as shown in

Figure 8, right), not source it from V3P3D (as shown in Figure 8, 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 Table 56. If more than one input is connected to the

same resource, the resources are combined using a logical OR.

The PB pin is a dedicated digital input. In addition, if the optical UART is not used, OPT_TX and OPT_RX can be

configured as dedicated DIO pins. Thus, in addition to the 16 general-purpose DIO pins (DIO4…DIO11,

DIO14…DIO21), there are three additional pins that can be used for digital input and output.

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