08M2 I2C Slave

[bpowell]

Hello Technical / Team,

I'm curious why the 20X2 (and other X2 parts) have the ability to be an I2C slave, but not the M2? Is it just a matter of code-space on the chip? Something else?

Thanks!

 

[JimPerry]

The various Picaxe models use different Microchip silicon - RevEd do as much as they can with each chip

 

[bpowell]

The various Picaxe models use different Microchip silicon - RevEd do as much as they can with each chip

The 20X2 and the 08M2 both have MSSP modules built into the silicon...they are both capable of being I2C slaves...but the functionality is only available in the 20X2...the 20X2 has a huge flash-storage...so I'm wondering if RevEd just had more "room" to put features in the 20X2?

I'm certainly amazed at all these chips can do...but wanted to ask the question.

 

[Technoman]

According to the Microchip doc, the 08M2 (PIC12F1840) has the capability to handle the I2C slave mode as pointed out by bpowell.

Probably a marketing policy is making this feature only available for the X series. For a small distributed application with a small number of I/O for each slave, the 20X2 (18 I/O) is bulky ; a market for a "08X2" ?

 

[srnet]

According to the Microchip doc, the 08M2 (PIC12F1840) has the capability to handle the I2C slave mode as pointed out by bpowell.

Technically feasible, yes.

Probably a marketing policy is making this feature only available for the X series. For a small distributed application with a small number of I/O for each slave, the 20X2 (18 I/O) is bulky ; a market for a "08X2" ?

Why probably ?

Might it be due to the X2 series having the memory space required to implement the I2C slave mode that the 12F1840 just does not have ?

the 20X2 (18 I/O) is bulky ; a market for a "08X2" ?

There may well be a market for such a device. Donate a few 10s of millons of £ to Microchip and they may consider developing one.

 

[Technoman]

Why probably ?

The M series is dedicated to education where applications are not complex and often use a single chip.

Is it technically feasible to add the I2C slave mode to this chip (firmware modification), leaving enough space for the program ? Only RevEd may answer this question.

 

[srnet]

Is it technically feasible to add the I2C slave mode to this chip (firmware modification) ?

Maybe if they removed some other feature, they would have the space to add the I2C slave in.

 

[Technical]

.so I'm wondering if RevEd just had more "room" to put features in the 20X2?

Indeed, the various features are mainly dependent on the memory space available for the firmware. In the case of the i2c slave you also need a scratchpad type RAM area as well. If Microchip produce an 8-pin part with double the program space of the existing chips then this may then become feasible.

 

[Technoman]

dependent on the memory space available...

scratchpad type RAM...

Could it be done with the PIC16F1825 (14M2) which has more memory and I2C slave capability?

 

[bpowell]

Indeed, the various features are mainly dependent on the memory space available for the firmware. In the case of the i2c slave you also need a scratchpad type RAM area as well. If Microchip produce an 8-pin part with double the program space of the existing chips then this may then become feasible.

Thanks Technical...I'd figured as much, but thought I'd ask the question!

My wish-list item would be to have the Picaxe editor add modules as-needed during programming...e.g, "Want I2C slave, but not ADC or one-wire communication? Okay...I2C module in, one-wire and ADC modules out..." It sounds so easy when typing it out, but I recognize this would be very difficult to implement in practice.

Don't get me wrong, this editor and the chips are amazing!