PIC16C717-I/SS View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC16C717-I/SS

18/20-Pin, 8-Bit CMOS Microcontrollers with 10/12-Bit A/D

Microchip Technology 

PIC16C717/770/771

9.2.19 CONNECTION CONSIDERATIONS FOR I2C

BUS

For standard-mode I2C bus devices, the values of

resistors Rp and Rs in Figure 9-39 depends on the fol-

lowing parameters

• Supply voltage

• Bus capacitance

• Number of connected devices

(input current + leakage current).

The supply voltage limits the minimum value of resistor

Rp due to the specified minimum sink current of 3 mA

at VOL max = 0.4V for the specified output stages. For

example, with a supply voltage of VDD = 5V+10% and

VOL max = 0.4V at 3 mA, Rp min = (5.5-0.4)/0.003 =

1.7 kΩ. VDD as a function of Rp is shown in Figure 9-39.

The desired noise margin of 0.1VDD for the low level

limits the maximum value of Rs. Series resistors are

optional and used to improve ESD susceptibility.

The bus capacitance is the total capacitance of wire,

connections, and pins. This capacitance limits the max-

imum value of Rp due to the specified rise time

(Figure 9-39).

The SMP bit is the slew rate control enabled bit. This bit

is in the SSPSTAT register, and controls the slew rate

of the I/O pins when in I2C mode (master or slave).

FIGURE 9-39: SAMPLE DEVICE CONFIGURATION FOR I2C BUS

VDD + 10%

RP

RP

DEVICE

RS RS

SDA

SCL

Cb=10 pF to 400 pF

Note: I2C devices with input levels related to VDD must have one common supply line to which the pull-up resistor is also connected.

TABLE 9-3: REGISTERS ASSOCIATED WITH I2C OPERATION

Address

Name

Bit 7

Bit 6

Bit 5 Bit 4 Bit 3

Bit 2

Bit 1

Bit 0 POR, BOR MCLR, WDT

0Bh, 8Bh,

10Bh,18Bh

INTCON

GIE

PEIE

T0IE INTE RBIE

T0IF

INTF

RBIF 0000 000x 0000 000u

0Ch

PIR1

—

ADIF

—

—

SSPIF CCP1IF TMR2IF TMR1IF -0-- 0000 -0-- 0000

8Ch

PIE1

—

ADIE

—

—

SSPIE CCP1IE TMR2IE TMR1IE -0-- 0000 -0-- 0000

0Dh

PIR2

LVDIF

—

—

—

BCLIF

—

—

CCP2IF 0--- 0--0 0--- 0--0

8Dh

PIE2

LVDIE

—

—

—

BCLIE

—

—

CCP2IE 0--- 0--0 0--- 0--0

13h

SSPBUF

Synchronous Serial Port Receive Buffer/Transmit Register

xxxx xxxx uuuu uuuu

14h

SSPCON WCOL SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0 0000 0000 0000 0000

91h

SSPCON2 GCEN ACKSTAT ACKDT ACKEN RCEN

PEN

RSEN

SEN 0000 0000 0000 0000

94h

SSPSTAT SMP

CKE

D/A

P

S

R/W

UA

BF

0000 0000 0000 0000

Legend: x = unknown, u = unchanged, - = unimplemented read as ’0’. Shaded cells are not used by the MSSP in I2C mode.

DS41120A-page 108

Advanced Information

© 1999 Microchip Technology Inc.

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