Rainbow Electronics MAX7360 User Manual

Page 12

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C-Interfaced Key-Switch Controller and LED

Driver/GPIOs with Integrated ESD Protection

MAX7360

12 _____________________________________________________________________________________

GPIO Constant-Current Setting Register (0x43)

The GPIO constant-current setting register sets the global

constant-current amount (see Table 17 in the Register

Tables section). Bits D1 and D0 set the global current

values from 5mA up to 20mA.

GPIO Output Mode Register (0x44)

The GPIO output mode register sets an output as either

a constant-current or non-constant-current output for

PORT[7:0] (see Table 18 in the Register Tables section).

Outputs are configured as constant-current outputs by

default to prevent accidental loading of an LED across

an unregulated output. The constant-current circuits

automatically turn off when not in use to reduce current

consumption.

Common PWM Register (0x45)

The common PWM register stores the common constant-

current output PWM duty cycle (see Table 19 in the

Register Tables section). The values stored in this register

translate over to a PWM duty cycle in the same manner

as the individual PWM registers (0x50 to 0x57). Ports can

use their own individual PWM value, or the common PWM

value. Write to this register to change the duty cycle of

several ports at once.

Rotary Switch Configuration Register (0x46)

The rotary switch configuration register stores rotary

switch settings for PORT7 and PORT6 (see Table 20 in

the Register Tables section). D7 determines whether

switch counts or a time delay will trigger an interrupt

if enabled. D[6:4] set the count or time amount to wait

before sending an interrupt. Bits D[3:0] set the debounce

cycle time for the rotary switch inputs. Debounce time

ranges from 0 to 15ms.

C Timeout Flag Register (0x48) (Read Only)

The I

C timeout flag register contains a single bit (D0),

which indicates if an I

C timeout has occurred (see Table

21 in the Register Tables section). Read this register to

clear an I

C timeout initiated interrupt.

GPIO Input Register (0x49) (Read Only)

The GPIO input register contains the input data for all of

the GPIOs (see Table 22 in the Register Tables section).

Ports configured as outputs are read as high. There is

one debounce period delay prior to detecting a transition

on the input port. This prevents a false interrupt from

occurring when changing a port from an output to an

input. The GPIO input register reports the state of all

input ports regardless of any interrupt mask settings.

Ports configured as an input have a 2FA internal pullup

to V

for PORT[5:0] and a 10FA internal pullup to V

for PORT[7:6].

Rotary Switch Count Register (0x4A) (Read Only)

The MAX7360 keeps a count of the rotary switch rotations

in two’s compliment format (see Table 23 in the Register

Tables section). The register values wrap around as the

count value switches from a positive to a negative value

and back again. The count resets to zero after an I

read to this register.

PORT0–PORT7 Individual PWM Ratio Registers

(0x50 to 0x57)

Each port has an individual PWM ratio register (0x50 to

0x57, see Table 24 in the Register Tables section). Use

values 0x00 to 0xFE in these registers to configure the

number of cycles out of 256 the output sinks current

(LED is on), from 0 cycles to 254 cycles. Use 0xFF to

have an output continuously sink current (always on).

For applications requiring multiple ports to have the

same intensity, program a particular port’s configuration

(0x45). New PWM settings take place at the beginning of

a PWM cycle, to allow changes from common intensity to

individual intensity with no interruption in the PWM cycle

PORT0–PORT7 Configuration Registers

(0x58 to 0x5F)

Registers 0x58 to 0x5F set individual configurations for

each port (see Table 25 in the Register Tables section).

Bits D7 and D6 determine the interrupt settings for the

inputs. Interrupts can assert upon detection of a logic

transition, a rising edge, or not at all. D5 sets the port’s

PWM setting to either the common or individual PWM

setting. Bits D[4:2] enable and set the ports’ individual

blink period from 0 to 4096ms. Bits D1 and D0 set a port’s

blink duty cycle.

Fading

Set the fade cycle time in the GPIO global configuration

Table 14 in the Register Tables section). Fade in increases

an LED’s PWM intensity in 16 even steps from zero to its

stored value. Fade out decreases an LED’s PWM intensity in

16 even steps from its current value to zero. Fading occurs

automatically in any of the following scenarios:
1) Change the common PWM register value from any

value to zero to cause all ports using the common

PWM register settings to fade out. No ports using

individual PWM settings are affected.

2) Change the common PWM register value to any value

from zero to cause all ports using the common PWM

PWM settings are affected.

3) Put the part out of shutdown to cause all ports to

fade in. Changing an individual PWM intensity during

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