OM13008,598 NXP Semiconductors, OM13008,598 Datasheet - Page 196

• Manufacturer Part Number: OM13008,598
• Description: BOARD LPC XPRESSO LPC122X
• Manufacturer: NXP Semiconductors
• Series: LPCXpressor

Specifications of OM13008,598

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 568-6642; OM13008

NXP Semiconductors
UM10441
User manual
11.9.2 Address Registers, ADR0 to ADR3
11.9.3 Address mask registers, MASK0 to MASK3
11.9.4 Comparator
11.9.5 Shift register, DAT
11.9.6 Arbitration and synchronization logic
These registers may be loaded with the 7-bit slave address (7 most significant bits) to
which the I
LSB (GC) is used to enable General Call address (0x00) recognition. When multiple slave
addresses are enabled, the actual address received may be read from the DAT register at
the state where the “own slave address” has just been received.
Remark: in the remainder of this chapter, when the phrase “own slave address” is used, it
refers to any of the four configured slave addresses after address masking.
The four mask registers each contain seven active bits (7:1). Any bit in these registers
which is set to ‘1’ will cause an automatic compare on the corresponding bit of the
received address when it is compared to the ADRn register associated with that mask
register. In other words, bits in an ADRn register which are masked are not taken into
account in determining an address match.
When an address-match interrupt occurs, the processor will have to read the data register
(DAT) to determine which received address actually caused the match.
The comparator compares the received 7-bit slave address with any of the four configured
slave addresses in ADR0 through ADR3 after masking. It also compares the first received
8-bit byte with the General Call address (0x00). If an a match is found, the appropriate
status bits are set and an interrupt is requested.
This 8-bit register contains a byte of serial data to be transmitted or a byte which has just
been received. Data in DAT is always shifted from right to left; the first bit to be transmitted
is the MSB (bit 7) and, after a byte has been received, the first bit of received data is
located at the MSB of DAT. While data is being shifted out, data on the bus is
simultaneously being shifted in; DAT always contains the last byte present on the bus.
Thus, in the event of lost arbitration, the transition from master transmitter to slave
receiver is made with the correct data in DAT.
In the master transmitter mode, the arbitration logic checks that every transmitted logic 1
actually appears as a logic 1 on the I
1 and pulls the SDA line low, arbitration is lost, and the I
from master transmitter to slave receiver. The I
pulses (on SCL) until transmission of the current serial byte is complete.
Arbitration may also be lost in the master receiver mode. Loss of arbitration in this mode
can only occur while the I
Arbitration is lost when another device on the bus pulls this signal low. Since this can
occur only at the end of a serial byte, the I
Figure 20
shows the arbitration procedure.
2
C block will respond when programmed as a slave transmitter or receiver. The
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Rev. 1.1 — 10 March 2011
2
C block is returning a “not acknowledge: (logic 1) to the bus.
2
C-bus. If another device on the bus overrules a logic
2
C block generates no further clock pulses.
2
Chapter 11: LPC122x I2C-bus controller
C block will continue to output clock
2
C block immediately changes
UM10441
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