Intel SPSH4 Technical Product Specification page 70

SCSI Bay Boardset
6.4.2.1 Special Function Registers
The 80C652 special function register space is the same as that on the 80C51 except that it
contains four additional SFRs. The added registers are S1CON, S1STA, S1DAT, and S1ADR.
In addition to these, the standard UART special function registers SCON and SBUF have been
renamed S0CON and S0BUF for clarity.
Since the standard 80C51 on-chip functions are the same on the 80C652, the SFR locations, bit
locations, and operation are unchanged. The only exception is in the interrupt enable and
interrupt priority SFRs. These have been changed to include the interrupt from the I
port.
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6.4.2.2 I C Serial Communication
2
The I C pins are alternate functions to port pins P1.6 and P1.7. Because of this, P1.6 and P1.7
on these parts do not have a pull-up structure as found of the 80C51. Therefore, P1.6 and P1.7
have open drain outputs on the 80C652.
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6.4.2.3 I C Electrical Input/Output Specification
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The I C bus allows communication between devices using different technologies that might also
use different supply voltages.
For devices with fixed input levels, operating on a supply voltage of +5V ±10%, the following
levels have been defined:
•
V = 1.5V (maximum input low voltage)
Ilmax
•
V = 3V (minimum input High voltage)
Ihmin
Devices operating on a fixed supply voltage different from +5V (e.g. I
input levels of 1.5V and 3V for V
For devices operating over a wide rage of supply voltages (e.g. CMOS), the following levels
have been defined:
•
V = 0.3V
Ilmax DD
•
V = 0.7V
Ihmin DD
For both groups of devices, the maximum output Low value has been defined:
•
V = 0.4V (max. output voltage Low) at 3ma sink current
Olmax
The maximum low-level input current at V
device is –10uA, including the leakage current of a possible output stage.
The maximum high-level input current at 0.9V
device is 10uA, including the leakage current of a possible output stage.The maximum
capacitance of both the SDA pin and the SCL pin of an I
58
and V respectively.
IL IH
(maximum input Low voltage)
(minimum input High voltage)
Olmax
SPSH4 Server System External Product Specification
of both the SDA pin and the SCL pin of an I
of both the SDA pin and SCL pin of an I
DD
2
C device is 10pf.
2
C serial
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L), must also have these
2
C
Revision 1.11
2
C