TimerSerial Vs hardware UART Code size

[SeuPay 17]

Doing some experiments with an older LaunchPad (rev 1.4).

With a MSP340G2553 (hardware UART):

 

Commpiling a small Sketch with serial communication found that the code size generated by the compiler

is smaller using TimerSerial than the code size used for hardware UART:

 

Target Board: LaunchPad w/ msp430G2452 (16MHz)

 

Erasing...

Programming...

Done, 1358 bytes written <---- Using TimerSerial

 

Target Board: LaunchPad w/ msp430G2553 (16MHz)

 

Erasing...

Programming...

Done, 1930 bytes written <---- Using hardware UART

 

any idea?

[cde 334]

Try putting the two sketchs on the same 2553 chip, do you get the same result?

[SeuPay 17]

There is one Sketch only.

Is compiled using diferent options (target Microcontroller).

Both of them are working correctly (taking care of inverting TXD and RXD lines ).

When the target is MSP430G2452, the compiler will use TimerSerial library because there is not a UART available.

The compiler produce a more compact code when simulate the UART, a strange result in my opinion. :?:

[energia 481]

This is due to USCIAB0TX_VECTOR and USCIAB0RX_VECTOR being shared between UART and I2C. Unfortunately the I2C ISR code is pulled into even if you only use UART. This results in an increase in size. This will be revisited for the next release to see if this can be done in a more elegant and code size optimal way.