RX610 Group
22. I
2
C Bus Interface (RIIC)
R01UH0032EJ0120 Rev.1.20
Page 717 of 1006
Feb 20, 2013
AL Flag (Arbitration Lost Flag)
This flag shows that bus mastership has been lost (loss in arbitration) due to a bus conflict or some other reason when a
start condition is issued or an address and data are transmitted. The RIIC monitors the level on the SDAn line during
transmission and, if the level on the line does not match the value of the bit being output, sets the value of the AL bit to 1
to indicate that the bus is occupied by another device.
The RIIC can also set the flag to indicate the detection of loss of arbitration during NACK transmission in master mode
or during data transmission in slave mode.
[Setting conditions]
<When master arbitration lost detection is enabled: ICFER.MALE = 1>
•
When the internal SDA output state does not match the SDAn line level at the rising edge of SCL clock except for
the ACK period during data (including slave address) transmission in master transmit mode (when the SDAn line is
driven low while the internal SDA output is 1 (the SDAn pin is in the high-impedance state))
•
When a start condition is detected while the ST bit in ICCR2 is 1 (start condition issuance request) or the internal
SDA output state does not match the SDAn line level
•
When the ST bit in ICCR2 is set to 1 (start condition issuance request) with the BBSY flag in ICCR2 set to 1.
<When NACK arbitration lost detection is enabled: ICFER.MALE = 1>
•
When the internal SDA output state does not match the SDAn line level at the rising edge of SCL clock in the ACK
period during NACK transmission in receive mode
<When slave arbitration lost detection is enabled>
•
When the internal SDA output state does not match the SDAn line level at the rising edge of SCL clock except for
the ACK period during data transmission in slave transmit mode
[Clearing conditions]
•
When 0 is written to the AL bit after reading AL = 1
•
When 1 is written to the IICRST bit in ICCR1 to apply an RIIC reset or an internal reset
Table 22.5 Relationship between Arbitration Lost Generation Sources and Arbitration Lost Enable Functions
ICFER
ICSR2
Error
Arbitration Lost Generation Source
MALE
NALE
SALE
AL
1
*
*
1
Start condition
issuance error
When internal SDA output state does not match SDAn line level when a
start condition is detected while the ST bit in ICCR2 is 1
When ST in ICCR2 is set to 1 with BBSY in ICCR2 set to 1
1
Transmit data
mismatch
When transmit data (including slave address) does not match the bus
state in master transmit mode
*
1
*
1
NACK
transmission
mismatch
When ACK is detected during transmission of NACK in master receive
mode or slave receive mode
*
*
1
1
Transmit data
mismatch
When transmit data does not match the bus state in slave transmit mode
[Legend]
*
: Don’t care
Summary of Contents for RX600 Series
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