Rainbow-electronics MAX7360 Bedienungsanleitung PDF herunterladen (Seite 10)

C-Interfaced Key-Switch Controller and LED

Driver/GPIOs with Integrated ESD Protection

MAX7360

10 _____________________________________________________________________________________

Key-Scan Controller

Key inputs are scanned statically, not dynamically,

to ensure low-EMI operation. As inputs only toggle

in response to switch changes, the key matrix can be

routed closer to sensitive circuit nodes.

The key-scan controller debounces and maintains a FIFO

of keypress and release events (including autorepeated

keypresses, if autorepeat is enabled). Table 2 shows the

key-switch order. The user-programmable key-switch

debounce time, and autosleep timer, is derived from the

64kHz clock, which in turn is derived from the 128kHz

oscillator. Time delay for autorepeat and key-switch

interrupt is based on the key-switch debounce time.

Keys FIFO Register (0x00)

The keys FIFO register contains the information pertaining

to the status of the keys FIFO, as well as the key events

that have been debounced (see Table 7 in the Register

Tables section). Bits D0–D5 denote which of the 64 keys

have been debounced and the keys are numbered as in

Table 1.

D7 indicates if there is more data in the FIFO, except

when D5:D0 indicate key 63 or key 62. When D5:D0

indicate key 63 or key 62, the host should read one more

time to determine whether there is more data in the FIFO.

Use key 62 and key 63 for rarely used keys. D6 indicates

if it is a keypress or release event, except when D5:D0

indicate key 63 or key 62.

Reading the key-scan FIFO clears the interrupt INTK

depending on the setting of bit D5 in the configuration

Configuration Register (0x01)

The configuration register controls the I

C bus timeout

feature, enables key-release detection, enables autowake,

and determines how INTK is deasserted. Write to bit D7

to put the MAX7360 into sleep mode or operating mode.

Autosleep and autowake, when enabled, also change the

status of D7 (see Table 8 in the Register Tables section).

Debounce Register (0x02)

The debounce register sets the time for each debounce

cycle, as well as setting whether the GPO ports are

enabled or disabled. Bits D0–D4 set the debounce time

in increments of 1ms starting at 9ms and ending at 40ms

(see Table 9 in the Register Tables section). Bits D5, D6,

and D7 set which of the GPO ports is enabled. Note the

GPO ports are enabled only in the combinations shown

in Table 9, from all disabled to all enabled.

Key-Switch Interrupt Register (0x03)

The interrupt register contains information related to the

settings of the interrupt request function, as well as the

status of the INTK output, which can also be configured

as a GPO. If bits D0–D7 are set to 0x00, the INTK output

is configured as a GPO that is controlled by bit D1 in the

port register. There are two types of interrupts, the FIFO-

based interrupt and time-based interrupt. Set bits D0–D4

to assert interrupts at the end of the selected number of

debounce cycles following a key event (see Table 10 in

the Register Tables section). This number ranges from

1–31 debounce cycles. Setting bits D7, D6, and D5 set

the FIFO-based interrupt when there are 4–16 key events

stored in the FIFO. Both interrupts can be configured

simultaneously and INTK asserts depending on which

condition is met first. INTK deasserts depending on the

status of bit D5 in the configuration register.

Ports Register (0x04)

The ports register sets the values of PORT2–PORT7

and the INTK port, when configured, as open-drain

Table 2. Key-Switch Mapping

PIN COL0 COL1 COL2* COL3* COL4* COL5* COL6* COL7*

ROW0

KEY 0 KEY 8 KEY 16 KEY 24 KEY 32 KEY 40 KEY 48 KEY 56

ROW1

KEY 1 KEY 9 KEY 17 KEY 25 KEY 33 KEY 41 KEY 49 KEY 57

ROW2

KEY 2 KEY 10 KEY 18 KEY 26 KEY 34 KEY 42 KEY 50 KEY 58

ROW3

KEY 3 KEY 11 KEY 19 KEY 27 KEY 35 KEY 43 KEY 51 KEY 59

ROW4

KEY 4 KEY 12 KEY 20 KEY 28 KEY 36 KEY 44 KEY 52 KEY 60

ROW5

KEY 5 KEY 13 KEY 21 KEY 29 KEY 37 KEY 45 KEY 53 KEY 61

ROW6

KEY 6 KEY 14 KEY 22 KEY 30 KEY 38 KEY 46 KEY 54 KEY 62

ROW7

KEY 7 KEY 15 KEY 23 KEY 31 KEY 39 KEY 47 KEY 55 KEY 63

*These columns can be configured as GPOs.

1 2 ... 5 6 7 8 9 10 11 12 13 14 15 ... 30 31

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