tmp19a44fda TOSHIBA Semiconductor CORPORATION, tmp19a44fda Datasheet - Page 448

• Manufacturer Part Number: tmp19a44fda
• Description: 32bit Tx System Risc
• Manufacturer: TOSHIBA Semiconductor CORPORATION

(Note)
Serial Bus Interface (SBI)
Do not write <MST> to "0" when it is "0." (Repeated start cannot be done.)
SCL (bus)
SCL pin
SDA pin
<LRB>
<BB>
<PIN>
16.6.5
Repeated start is used when a master device changes the data transfer direction without terminating the
transfer to a slave device. The procedure of generating a repeated start in the master mode is described
below.
First, set SBICR2 <MST, TRX, BB> to "0" and write "1" to <PIN> to release the bus. At this time, the
SDA pin is held at the "H" level and the SCL pin is released. Because no stop condition is generated on
the bus, other devices think that the bus is busy. Then, test SBISR <BB> and wait until it becomes "0"
to ensure that the SCL pin is released. Next, test <LRB> and wait until it becomes "1" to ensure that no
other device is pulling the SCL bus line to the "L" level. Once the bus is determined to be free this way,
use the steps described above in (16.6.2 Generating the Start Condition and a Slave Address) to generate
the start condition.
To satisfy the setup time of repeated start, at least 4.7- μ s wait period (in the standard mode) must be
created by the software after the bus is determined to be free.
(Note) X: Don't care
SBICR2
if SBISR<BB> ≠ 0
Then
if SBISR<LRB> ≠ 1
Then
4.7 μ s Wait
SBICR1
SBIDBR
SBICR2
Repeated Start Procedure
Fig. 16.14 Timing Chart of Generating a Repeated Start
← 0 0 0 1 1 0 0 0
← X X X 1 0 X X X
← X X X X X X X X
← 1 1 1 1 1 0 0 0
"0"
"0"
"0"
"1"
7 6 5 4 3 2 1 0
→
→
→
→
9
<MST>
<TRX>
<BB>
<PIN>
TMP19A44 (rev1.3) 16-24
Releases the bus.
Checks that the SCL pin is released.
Checks that no other device is pulling the SCL pin to the
Selects the acknowledgment mode.
Sets the desired slave address and direction.
Generates the start condition.
"L" level.
"1"
"1"
"1"
"1"
→
→
→
→
4.7 μ s (min.)
<MST>
<TRX>
<BB>
<PIN>
TMP19A44
Start condition
2010-04-01