TMPR3916 Datasheet, PDF (184/225 Pages) Toshiba Semiconductor – 32-Bit TX System RISC TX39 Family TMPR3916

Chapter 10 Asynchronous Serial Interface (UART)
10.1.14 Multi Controller Systems
When UMODE in the Line Control Register (SILCR) is 0x2 or 0x3, the UART changes into the multi
controller system mode. In a multi controller system, the master controller sends data to the selected
slave controllers. The slaves will be selected by sending an address ID before sending the data. Non-
selected slave controllers will ignore the data. Setting the WUB of the transmit frame to 1 indicates the
transmission of an address ID. Data frames, instead, will have the WUB set to 0. It is up to the software
to compare the addresses and eventually enable the reception of Data Frames.
Protocol of multi controller system:
(1) Master and slave controllers must have the UMODE field 10 or 11 in the Line Control Register to
operate in multi controller mode.
(2) Software sets the RWUB in the Line Control Register to 1 – for each slave controller – to be ready
to receive the address ID frame from the master controller.
(3) Software sets the WUB of the transmit frame to 1 (Line Control Register WUB=1) – in the master
controller – to send the slave controller address ID (7- or 8-bit length).
(4) An interrupt is generated in a slave controller when RWUB in Line Control Register is 1 and WUB
of the received data frame is 1 (receive data is an address frame). The software compares its
address ID with the received address ID and sets RWUB to 0 when both match. The last operation
enables the selected slave to receive data frames.
(5) Then software must set the WUB of the Line Control Register to 0 to enable the transmission of
data frames for the master controller. If this operation is not performed the WUB in the transmitted
frames will be 1, and the slaves will understand the incoming frames as address frames.
When the selected slave controller (i.e. the controller whose address matched with the one sent by the
master) receives data, an interrupt is generated.
A non selected slave controller will have the RWUB still set to 1, incoming data frames will be
ignored.
The slave controllers can send data only to the master controller.
An example of the multi controller system configuration is shown in Figure 10.1.5
Master
SOUT SIN
TX
RX
RX TX
SIN SOUT
Slave#1
RX TX
SIN SOUT
Slave#2
RX
TX
SIN SOUT
Slave#3
Figure 10.1.5 Example Configuration for Multi Controller System
IMPORTANT: The TMPR3916 does not have Open Drain capability on its output pins. A configuration as
the one depicted in Figure 10.1.5 is possible only if external logic is added on the board.
10-9
Preliminary