Artesyn MVME5100, Programmer'S Reference Manual, Page: 256 / 318

System Memory Controller (SMC)
MVME5100 Single Board Computer Programmer’s Reference (6806800H17B )
256
3.3.3.18 I
2
C Clock Prescaler Register
I2_PRESCALE_VAL
I2_PRESCALE_VAL is a 16-bit register value that will be used in the following formula for
calculating frequency of the I
2
C gated clock signal:
I
2
C CLOCK = SYSTEM CLOCK/
(I2_PRESCA1)/2
After power-up, I2_PRESCALE_VAL is initialized to $1F3 which produces a 100 KHz I
2
C gated
clock signal based on a 100.0 MHz system clock. Writes to this register will be restricted to
4-bytes only.
3.3.3.19 I
2
C Control Register
i2_start
Table 3-36 I
2
C Clock Prescaler Register
Address $FEF80090
Bit
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
Name I2_PRESCALE_VAL
Operation READ ZERO READ ZERO READ/WRITE
Reset X X $01F3 P
Table 3-37 I
2
C Control Register
Address $FEF80098
Bit
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
Name
0 0 0 0 i2_st
ar
t
i2_st
op
i2_a
ck
ou
t
i2_e
nb
l
Operation
READ ZERO READ ZERO READ ZERO
R R R R R/W R/W R/W R/W
Reset X X X
X X X X 0 PL 0 PL 0 PL 0 PL