Part Number: TMS570LC4357-EP
Other Parts Discussed in Thread: TMS570LC4357, THVD1452
I am trying to connect the RS-485 transceiver THVD1452 to the microcontroller TMS570LC4357 Hercules
. As shown at the datasheet of the THVD1452 i am looking for the DIR pin on the microcontroller but I cannot find such pin.
I have followed figure 38 from the datasheet of THVD1452 but I cannot identify the DIR pin on the microcontroller
Hi Anastasios,
There won't be any specific direction pin, you can use simple GIO as a direction pin.
DE is the 'Driver Enable' pin and must be pulled high while you're transmitting data.
RE is the 'Receiver Enable' pin and must be pulled low whenever you want to be able to receive data. Because it is an active low input of the THVD1452.
In above picture, two application pictures are given, first one is half-duplex communication and second one is full-duplex communication.
In Half-duplex communication both transmission and reception will not happen simultaneously, only either transmitting or receiving will happen at a time. That is the reason here both DE and RE were tied together and given to the one GIO pin of the controller. So, here controller will do the following thing, whenever it wants to transmit some data to the RS485, then it will make the direction pin to the High and send the data through Tx pin and in remaining time it can just make the DIR pin low and that enables the receiver and can receive the data.
In Full-duplex communication both transmission and reception will happen simultaneously. Both transmitting and receiving can happen in any given time. So that is the reason here DE and RE were connected to the two different GIO pins of the controller. So here the controller can make both enable(DE as 1 and RE as 0) and can do the transmission and reception simultaneously.
I hope this clarifies the working of the both the applications, so now if you really want to do the half duplex communication with your RS485 then please tie the DE and RE together and give to the one of the GIO pin of the controller, which will act as a DIR pin.
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Thanks & regards,
Jagadish.
