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 memory
and is mirrored in a volatile memory
. 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.)
0-3
4-6
7
8 – 15
-
Volatile Memory Address
Range
(Register no.)
16 – 19
20 – 22
23
-
24 – 31
Description
Application parameters
Trim values, factory set
Device Address
Chip ID, factory set
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
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
15
VMODE
14
TPER
TSET
13
MODE
12
11
SOFF
CDET
10
DRATE
9
8
7
TSTMP
6
5
SENSH
4
3
TPULSE
2
1
POL
SENS IVCOFF SLOW
C2X
SENSN / VTHRLED
0
FUSEBIT
FUSEBIT
FUSEBIT
Application
parameters
Trimming
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
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
EPC [ ESPROS PHOTONICS CORP ]
