Two Issues with PICbasic's Efficiency

[mackrackit]

I am not sure if doing the I2C in ASM will help much. PBP for the most part is pretty efficient, It just takes a lot of bit shifting to do I2C no matter what. Take a look at the ASM generated by PBP and see what you think.

In your case I am thinking the fewer the I2C reads and writes no matter what language will be key. And that brings up adding the RTC... More I2C???

Another thought.
If the system has a few seconds of dead time now and then have more than on array to save the data in from the sensor. When ever there is time to spare write the oldest array to EEPROM and keep going. Kind of a home made interrupt.

And like Alan Said about FRAM. Could be what you need.

[Melanie]

It is a feature of SERIAL EEPROM like the internal PIC EEPROM or external EEPROM (like the 24LC64 and similar etc) that require (up to) 10mS for a WRITE operation (consult the Datasheet of the EEPROM you are using for the actual timing). All the worlds fastest Assembly routines will not help you. You must use a faster hardware product like Alain suggested.

[Normnet]

Or else, M25P32 from ST ...

I believe ST sold the M25P line to Numonyx and the line has been upgraded to the faster M25PE... series.
See the M25PE80 for a sample data sheet.
It's rated at writing 256 bytes in 11 ms.
For M25P code example see M25P32 (warning other compiler).

A full 256 byte per write is probably required however.
Since only erase can convert 0 to 1's overwriting previous of new and following of new bytes with 1's can simulate a one byte write.
Perhaps a low priority interrupt could do the 256 byte write in the background.


Norm

[Normnet]

M25PE80... The memory can be written or programmed 1 to 256 bytes at a time.

Improved over old M25P series?
I found with the previous M25P series after many 1 byte writes errors crept
in thus a full 256 byte sector write was used.

Norm

[hankshone]

Improved over old M25P series?
I found with the previous M25P series after many 1 byte writes errors crept
in thus a full 256 byte sector write was used.

Norm

Thanks Norm the your suggestions and the sample codes. IN the manual it sounds like 1~256 is a flexiable range that can be written. Any way I will try it out later.

[hankshone]

It is a feature of SERIAL EEPROM like the internal PIC EEPROM or external EEPROM (like the 24LC64 and similar etc) that require (up to) 10mS for a WRITE operation (consult the Datasheet of the EEPROM you are using for the actual timing). All the worlds fastest Assembly routines will not help you. You must use a faster hardware product like Alain suggested.

Sounds good. The EEPROMs require a 5ms wirting circle typically from Microchips. While it can be reduced to about 3ms as I tried.

[hankshone]

I am not sure if doing the I2C in ASM will help much. PBP for the most part is pretty efficient, It just takes a lot of bit shifting to do I2C no matter what. Take a look at the ASM generated by PBP and see what you think.

In your case I am thinking the fewer the I2C reads and writes no matter what language will be key. And that brings up adding the RTC... More I2C???

Another thought.
If the system has a few seconds of dead time now and then have more than on array to save the data in from the sensor. When ever there is time to spare write the oldest array to EEPROM and keep going. Kind of a home made interrupt.

And like Alan Said about FRAM. Could be what you need.

Yes, Alian is right and hardware is the core constrain. I did some revise for the previous codes like reading the accelerometer(six bytes register for three axes) in one I2C read, and the same pracitice for I2C write. The final speed improved to about 150Hz, and then later I started to work on something else for a long time... I think it is my time to crack this trick and will see what's the maximum I will get later. Thanks a lot!~