MPR083

Sensors

Freescale Semiconductor

17

Preliminary

6

Output Mechanisms

6.1

Introduction

The MPR083 has three primary methods for reporting data in addition to an IRQ output that is described in Chapter 7. The three

output systems are described in this section.

6.2

Instantaneous

The Instantaneous output shows the current status of the user interface. This information is displayed in terms of the current

rotary position that is touched. Only one touch can be shown at a time.

6.2.1

Rotary Status Register

Rotary Status Register is 0x02.

Figure 20. Rotary Status Register

6.3

Buffered

The Buffered output is done through a FIFO. The FIFO will buffer every touch that occurs up to 30 values before the buffer

overflows and data is lost. Any time data is read from the FIFO it is pulled from the buffer and the next item becomes available.

The buffer can be cleared (NDF goes high) by either reading the last entry or attempting to write to the register.

The buffer settings are configured in the Rotary Configuration Register as described in Section 3.4.

6.3.1

FIFO Register

The FIFO Register is a read only register for determining the current status of the rotary. Any time a write is issued to this register

Figure 21. FIFO Register

7

6

543210

R0

0

0

SF

CP

W

Reset:

0

0

000000

= Unimplemented

Table 12. Rotary Status Register Field Descriptions

Field

Description

4

SF

Status Flag – The Status Flag shows when the rotary is currently detecting a touch.

0 Rotary is not currently detecting a touch

1 Rotary is currently detecting a touch

3:0

CP

Current Position – The Current Position represents the electrode that is currently

being touched.

0000 Encoding 0 – Electrode 1 is currently touched

~

0111 Encoding 7 – Electrode 8 is currently touched

7

6

543210

R

MDF

NDF

OF

TRF

BP

W

Reset:

0

1

000000

= Unimplemented