hser functions in 40x2 - others??

[hwholmes]

I have finally succeded after several hours of trying almost every thing else but what worked in geting my computer to communicate using hyperterminal with the 40x2 on the hser port.
Since I was also using the serial download link to get information back while testing I then tried to swap the usb to ttl interfaces from one to the other to see if the data streams would work through the other computer interface.

To my amazement it worked just by lifting the cables and swaping them.

I say I am amazed because with no diferences between the interfaces they would work on the ser link but on the hser link the mode was set to invert both in and out. This raises the question in my mind "WHY are the default hserand the ser ports different?" i.e. I would assume (since invert was not fully available in earlier release) that the inverted hser mode %111 is the exception - not thedefault but if I don't invert then I cannot read the data from the hser port but it works on the ser download port with no configuration at all.
As I say - I have it working - it took a while to fathom it out - but I am curious why?
Bert

 

[Technical]

The hserout/in default polarity is an in built feature of the PIC chip internal EUSART silicon module. Some PICAXE chips cannot invert serin as that feature was not made available by Microchip in the actual silicon in the PIC until quite recently.

 

[hwholmes]

I understood that but I don't understand why the default for the ser port is different fron the hser port.

 

[hippy]

That's down to differences between hardware designers ( Microchip ) and software developers ( Rev-Ed ).

The hardware HSER was designed by Microchip to be used in a system which requires an inverter such as a MAX232 to be used when connecting the hardware serial lines to a PC, the software was designed by Rev-Ed so that the chip could could connect through a non-HSER pin directly to a PC without the inconvenience or extra cost of a MAX232 or similar, just needing a two resistor interface.

Microchip seem to have recently realised that chips which can connect directly to a PC are very useful to have and now provide a means to invert the polarity on some of their chips but the default operation of the hardware remains as it initially was for backwards compatibility.

 

[hwholmes]

Microchip seem to have recently realised that chips which can connect directly to a PC are very useful to have and now provide a means to invert the polarity on some of their chips but the default operation of the hardware remains as it initially was for backwards compatibility.

Thank You - now it makes sense