r5f21368sdfp Renesas Electronics Corporation., r5f21368sdfp Datasheet - Page 465

• Manufacturer Part Number: r5f21368sdfp
• Description: Renesas Mcu R8c Family / R8c/3xt-a Series
• Manufacturer: Renesas Electronics Corporation.

Under development
R8C/36T-A Group
R01UH0240EJ0001 Rev.0.01
Apr 28, 2011
20.3.3.11 Control in Multimaster Operating Environment
(1) Arbitration
Mismatch of the transmit data and SDA2 pin input data is checked synchronously with the rising edge of
SCL. Use the ABC bit in the U2SMR register to select the timing at which the ABT bit in the U2RB
register is updated. If the ABC bit is 0 (update every bit), the ABT bit is set to 1 at the same time a
mismatch is detected during check. When the ABC bit is set to 1 (update every bit), if a mismatch is
detected even once during check, the ABT bit is set to 1 at the falling edge of the 9th bit of the clock. If the
ABT bit needs to be updated every byte, set the ABT bit to 0 after detecting acknowledge for the first byte
before transferring the next data.
If the ALS bit in the U2SMR2 register is set to 1 (SDA output stops), arbitration is lost, in which case the
SDA2 pin is placed in the high-impedance state at the same time the ABT bit is set to 1. When this
function is used to turn SDA2 output off, it can be cancelled by setting either the ALS bit or ABT bit to 0.
However, while this function is enabled, even the timing of an acknowledge will be determined as an
arbitration lost and cause output to be turned off. Therefore, set the ABT bit to 0 before transmitting the
next byte. Set the ABC bit to 0 when using this function. In a multimaster operating environment, always
set the ABC bit to 0 and the ALS bit to 1.
Preliminary document
Specifications in this document are tentative and subject to change.
20. Serial Interface (UART2)
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