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
Volatile Memory Address
Range
Description
(Register no.)
(Register no.)
0 - 3
4 - 6
7
16 – 19
20 – 22
23
Application parameters
Trim values, factory set
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:
ROM RAM
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
0
1
2
3
4
5
6
16 VMODE
MODE
SOFF
DRATE
TSTMP
TPULSE
POL FUSEBIT
FUSEBIT
17
18
19
20
21
22
TPER
TSET
Application
parameters
SENS IVCOFF SLOW
C2X
SENSH
SENSN / VTHRLED
FUSEBIT
CDET
Trimming
7
8
9
10
11
12
13
14
15
23
24
25
26
27
28
29
30
31
Address
Device Address
Chip ID
Chip ID
Figure 12: Detailed memory map
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
5
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.
Hereinafter called RAM.
© 2011 ESPROS Photonics Corporation
Characteristics subject to change without notice
11
Datasheet epc12x - V2.1
www.espros.ch
EPC [ ESPROS PHOTONICS CORP ]
