EEPROM WriteWait

william chan

Hey Mike,

Why does the WriteWait method in Basic_I2C_Driver require 3 input parameters?
I think it should be simplified to 2 input parameters.

I tried using eeprom.WriteWait(eeprom#bootpin,eeprom#eeprom,loc) where loc is the location of the last WriteLong, but it seems to be unstable.
Should use zero instead for the 3rd parameter?
Replacing the WriteWait with waitcnt(clkfreq/40 + cnt) solves the stability problem.

But i was hoping to use WriteWait to minimize the total writing time of a large array. (1024 longs)

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Mike Green

The WriteWait statement has 3 parameters like other EEPROM functions:

1) The pin # of the I2C bus to be used (CLK pin # with DTA pin # the next highest)

2) The device select code for the EEPROM. This includes a device number (0-7)

3) An EEPROM address with blocks of 64K using separate select codes. Note that the bits representing the block # are combined with the device select code's device number so you can use either to select a memory.

The 3 parameters were used to make the different calls (READ / WRITE / WAIT) look and act similarly.

As usual for any sort of problem, it's important to give schematics, program source, and enough of a description so others can understand what's happening. WriteWait uses a feature of all current EEPROMs, that the EEPROM will stop responding during a write cycle until the cycle is finished. WriteWait simply attempts to start a read operation by selecting the device, then a memory location, but quitting before the read is actually done.

william chan

Is it necessary to call WriteWait in a loop until it's return value is zero?

I think that could be my problem......

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Mike Green

Yes, look at the example in the comments at the beginning of the object source. It provides for a timeout in case there's an error.