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Is it possible to receive data when TRMDn = 1 ?

Latest Updated: 03/20/2017


The following is described in 11.3.3 of the V850E/MA1 Hardware User's Manual (U14359EJ4V0UM00 (4th edition)):

(3) Serial I/O shift registers (SIO0 to SIO2) and
(4) Reception-only serial I/O shift registers (SIOE0 to SIOE2)

In the explanation above, the operation when TRMDn = 0 for the CSIMn register is described but no description is made for when TRMDn = 1.
Is it possible to receive data when TRMDn = 1 ?


Yes, reception as well as transmission can be executed at the same time when TRMDn = 1.
To start communication when TRMDn = 1, you have to write to SOTBn.
Reading SIOn does not start communication.
On the other hand, when TRMDn = 0, reading SIOn will start communication.
Therefore, SIOEn is prepared for when you want to read data without starting communication.
That is, when TRMDn = 1, SIOEn is not needed. That is why it is not described.
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