JB16 I2C

[AGIO]

This is a question for anyone who has been using or has used HC08 JB16 microcontroller. I've been using it for over a year now (specially because it has USB) and something caught my attention some time ago... there is no I2C or SPI serial interface! If you read the "Buy/Parametrics" tab here

  http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=68HC908JB16&nodeId=016246844976637583...

you can see that the I2C or SPI interface is specified for all versions (part numbers) as well as the SCI serial interface. But when you open JB16's datasheet... only the SCI serial interface is specified and there are no registers for the other two. So, my questions are:

Does the JB16 microcontroller include I2C interface?
Is there any way that you can implement an I2C interface using SCI interface and that is why Freescale specifies SPI and I2C but only details SCI in the datasheet ?

My partner and I decided to implement an I2C interface using bit banging... but shouldn't the JB16 include these routines and registers as Freescale specifies? We decided to upgrade our project and code using the S08JM microcontroller but I still want to know if I'm mistaken or the specifications are not reliable. Thanks to anyone that can answer these two questions.

[bigmac]

Hello,

The datasheet would be the primary document, and should take precedence over other summary information.  So you are correct about the absence of both SPI and IIC modules within the 908JB16 device. 

The only way to achieve either function would be to bit-bang.  SPI operation is quite simple, but IIC is a little more complex.

The operation of IIC is totally different from SCI operation.

Regards,

Mac

[AGIO]

Thanks bigmac for answering so soon... My first thought was what you have posted but I wanted to know if I was right about that as I am not an experienced microcontroller user and sometimes some issues are
"implicit" amongst experienced users. My project partner and I wrote the code to implement I2C and you are right about the complexity of it... it's easy to understand but not that easy to implement and make it work as it should with all it's features. It's a shame Freescale didn't decide to add I2C to it as it is a really versatile microcontroller and easy to use and program. I think they decided to make a complete version of it with the S08JM, so I'm working on it and lucky me that it's programmer can be built using the very same JB16.
Thanks again.
Agio.

[bigmac]

Hello Agio,

Keep in mind that the '908JB16 device is from an earlier family of MCU that has been available for a number of years.  In contrast, the '9S08JM60 is from the current 8-bit family, and is a recently introduced device.

For software I2C, the following application notes may be of interest.  However, the code presented within each document is in assembler.

AN1820  Software I2C communications

AN2509  I2C Slave on the HC908QT/QY family MCU

Regards,

Mac