Overclock & FullduplexSerial Object
greybeard
Posts: 65
I've put together a couple of Propeller Apps that use the serial port exclusively to communicate with a Windows App using the Windows serial API which has specific baud rate values. I am currently useing the Propelller running with a 5 MHz crystal. I'm about to start to experimenting with over-clocking the Propeller and would like to know what, if any, changes that I need to the make to the FullDuplexSerial spin object ( or other spin serial objects) to get make sure things continue working properly. I believe the Propeller baud rate is based upon the sysem clock thus may need a 'tweeking' somewhere to get the correct baud rate. I am currently working reliably with a 115200 baud rate.
I'm not looking to overclock drastically. The postings I have seen suggest that a 6.25 MHz Crystal replacement will yield a 100 MHz Propeller and seems to be reliable. I have a couple of the 6.25 MHz crystals to start experimenting with. I also have a couple of 6.144 Mhz Crystals which would produce a 98.304 Mhz Propeller (an odd frequency to work with but may be managable -- that's why it's called experimenting). If the 100 Mhz propeller functions reliably, the 98.304 Mhz should work well also but may make other timing difficult.
The Windows API apparently supports a baud rate at least twice 115200 baud. I would also like to increase the Propeller ouput baud rate, if possible, and would apperciate any pointers to accoplish that. I don't believe just overclocking the Propelleer will lead to an incrase in the baud rate but may be a necessary first step. Any suggestions or comments??
I'm not looking to overclock drastically. The postings I have seen suggest that a 6.25 MHz Crystal replacement will yield a 100 MHz Propeller and seems to be reliable. I have a couple of the 6.25 MHz crystals to start experimenting with. I also have a couple of 6.144 Mhz Crystals which would produce a 98.304 Mhz Propeller (an odd frequency to work with but may be managable -- that's why it's called experimenting). If the 100 Mhz propeller functions reliably, the 98.304 Mhz should work well also but may make other timing difficult.
The Windows API apparently supports a baud rate at least twice 115200 baud. I would also like to increase the Propeller ouput baud rate, if possible, and would apperciate any pointers to accoplish that. I don't believe just overclocking the Propelleer will lead to an incrase in the baud rate but may be a necessary first step. Any suggestions or comments??
Comments
As long as you define your clock constants correctly, the serial driver should compute the timing needed at various baud rates for you.
A lot (most) have this kind of calculation. This is from Parallax Serial Terminal.
I've noticed the name "bit_ticks" or a similar name is pretty universal for the number of clock cycles per bit of data sent or received. I suppose it would be nice (as in, it would work better), at very fast baud rates, if the clock frequency was divisible by "baudrate".