epc120

Parameter Memory

The epc120 device contains a memory to store the application parameters. The following classes of data are stored on each device:

•

Unique chip ID and chip adjustments (factory set)

•

Physical device address in the application, representing the beam number

•

Application parameters

This data can be permanently stored in a read-only memory4 and is mirrored in a volatile memory5. At power up, the data (except the chip ID)

is copied from the ROM to the RAM. During operation, the data from the RAM is used. Both memories are organized in 16 registers at 16 bits

each. The data can be accessed on a 16-bit register base. The following table shows the memory organization:

Non-Volatile Memory Address

Range

(Register no.)

Volatile Memory Address

Range

(Register no.)

Description

0 - 3

16 – 19

Application parameters

4 - 6

20 – 22

Trim values, factory set

7

23

Device Address

8 – 15

-

Chip ID, factory set

-

24 – 31

For factory test purpose. Read only.

Table 2: Memory map overview

As shown in the table above, registers 0 – 3 and 7 are used for configuring the chip in the application. Before the devices can be used in a

given light curtain system, the required application parameters and the physical address of the chip in the system have to be stored into the

devices memories. The following table shows a parameter memory overview:

Parameters in white fields only shall be programmed. Never change the memory content of gray marked cells. Because only complete

registers can be programmed, the bits which are gray marked must be set to zero.

The RAM can only be written, if the corresponding ROM memory hasn’t been written before or if the volatile mode is active (VMODE, refer to

Table 3 on page 11). The last bit of each 16-bit ROM register serves as write inhibit bit. To write to the ROM, the microcontroller has to write to

the RAM first. From there, the microcontroller can first double check the data integrity. When a memory section is verified, the content can be

transferred from the RAM memory using the command PROG to the ROM (refer to chapter Command PROG).

The device is fully operational as well without programming the ROM but data will be lost at power down. Operating the chips in this mode is

helpful during the development of the product. However, in the final application, the parameters must be stored into the ROM memory.

4 The non-volatile memory is a one-time-programmable memory (OTP). Once the memory is programmed, the programmed values cannot

be overwritten anymore! This memory type is hereinafter called ROM.

5 Hereinafter called RAM.

© 2011 ESPROS Photonics Corporation

Characteristics subject to change without notice

11

Datasheet epc12x - V2.1

www.espros.ch

Figure 12: Detailed memory map

ROM RAM

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

0

16

VMODE

MODE

SOFF

DRATE

TSTMP

TPULSE

POL FUSEBIT

1

17

TPER

FUSEBIT

2

18

TSET

SENS IVCOFF SLOW

SENSH

SENSN / VTHRLED

FUSEBIT

3

19

CDET

C2X

4

20

Trimming

5

21

6

22

7

23

Address

Device Address

8

24

Chip ID

Chip ID

9

25

10

26

11

27

12

28

13

29

14

30

15

31

Application

parameters