Nxp Semiconductors PCA9665 User Manual
PCA9665_2
© NXP B.V. 2006. All rights reserved.
Product data sheet
Rev. 02 — 7 December 2006
15 of 91
NXP Semiconductors
PCA9665
Fm+ parallel bus to I
2
C-bus controller
7.3.2.6
The I
2
C-bus mode register, I2CMODE (indirect address 06h)
I2CMODE is an 8-bit read/write register. It contains the control bits that select the correct
timing parameters when the device is used in master mode (AC[1:0]). Timing parameters
involved with AC[1:0] are t
timing parameters when the device is used in master mode (AC[1:0]). Timing parameters
involved with AC[1:0] are t
BUF
, t
HD;STA
, t
SU;STA
, t
SU;STO
, t
HIGH
, t
LOW
.
Remark: Change from an I
2
C-bus mode to a slower one (Fast-mode to Standard-mode,
for example) will cause the HIGH and LOW timings of SCL to be violated. It is then
required to program the I2CSCLL and I2CSCLH registers with values in accordance with
the selected mode.
required to program the I2CSCLL and I2CSCLH registers with values in accordance with
the selected mode.
[1]
I2CSCLL and I2CSCLH values in the table also represents the minimum values that can be used for the
corresponding I
corresponding I
2
C-bus mode. Use of lower values will cause the minimum values to be loaded.
[2]
Using the formula
Table 23.
I2CMODE - I
2
C-bus Mode register (indirect address 06h) bit allocation
7
6
5
4
3
2
1
0
-
-
-
-
-
-
AC1
AC0
Table 24.
I2CMODE - I
2
C-bus Mode register (indirect address 06h) bit description
Bit
Symbol
Description
7:2
-
Reserved. When I2CMODE is read, zeroes are read. Must be written
with zeroes.
with zeroes.
1:0
AC[1:0]
I
2
C-bus mode selection to ensure proper timing parameters (see
AC[1:0] = 00: Standard-mode AC parameters selected.
AC[1:0] = 01: Fast-mode AC parameters selected.
AC[1:0] = 10: Fast-mode Plus AC parameters selected.
AC[1:0] = 11: Turbo mode. In this mode, the user is not limited to a
maximum frequency of 1 MHz.
maximum frequency of 1 MHz.
Table 25.
I
2
C-bus mode selection example
I2CSCLL
(hexadecimal)
(hexadecimal)
I2CSCLH
(hexadecimal)
(hexadecimal)
I
2
C-bus frequency
(kHz)
AC[1:0]
Mode
9D
86
99.9
00
Standard
2C
14
396.8
01
Fast
11
09
952.3
10
Fast-mode Plus
0E
05
11
Turbo mode
f
SCL
1
T
osc
I 2CSCLL
I 2CSCLH
+
(
)
t
r
t
f
+
+
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