A few questions before new project with MCF52233

[efk]

Hello,

I am a newbie regarding Coldfire. I have to start a new project. I found 5 different µp (from different brands) able to make the job, and I am most interested with the MCF52233 model, which seems to be the best for my requirement. I read several times its pdf files and I think I got already the answers, however in order to be 100% sure, could you please confirm these points:

1 - I know almost nothing actually regarding ethernet (I will learn soon), but it seems the MCF52233 is one of the best µp for this. I guess you will agree for that point ?

2 - I read that division instruction (divu) is not available on all v2 coldfire µp, but it seems to be available on MCF52233. Is divu effectively available on MCF52233 ?

3 - I would like to use 2 uarts at 250Kb speed (with dma). I read dma is ok for uarts (good). And I calculated I have to use a quartz of 56MHz to get 250Kb (to get the fastest authorized µp clock). Is it right ?

4 - the real-time clock stores the day number into a 16bits register, and it does not store month and year. Is it possible to calculate weekday, month and year from this 16bits register ?

5 - is it possible to add a serial (spi) flash ram ?

Thank you in advance.

Regards.
Bob.

[efk]

Dear Mark,

Thank you for your answers. I took some time to reply because I made some more research.

1 - understood. I will study that point later (I need to learn more about ethernet

before) to check if these 2 points are not a problem for my requirement. Anyway, my requirement for web server feature is basic, so I think this would be ok.

2 - I checked again. DIVU seems to be available on that chip.

3 - it seems there is the possibility to multiply the reference clock (25MHz) by 9/4

with RFD = 011 (/8) and MFD = 111 (18*). This makes a clock of 56.25MHz (I guess this clock speed is allowed), and an uart clock of 251,1Kb (with 7 into USR_UCSR). Because 234Kb or 267Kb were not acceptable instead of 250Kb.

4 - I did not found the answer. My be I will place a new post for this.

5 - understood

I took a look at the uTasker. It seems very interesting. I will take more time to study it, and I will come back to you later.

Than you again for your help.
Bob.

[mjbcswitzerland]

Hi Bob

1 - I know almost nothing actually regarding ethernet (I will learn soon), but it seems the MCF52233 is one of the best µp for this. I guess you will agree for that point ?

- The internal EMAC is very good. The internal PHY is usefuly since it is on board and thus needs no external one. However there is a problem in some cases when trying to use it in autonegotation mode - see the freescale errata.
A external PHY is sometimes also a good alternative since they often offer additional features such as auto crossover which you don't get in the device.

2. Don't know the instruction set so won't answer here.

3 - I would like to use 2 uarts at 250Kb speed (with dma). I read dma is ok for uarts (good). And I calculated I have to use a quartz of 56MHz to get 250Kb (to get the fastest authorized µp clock). Is it right ?

- Be careful with the quarz. To use Ethernet you MUST use a 25.00000MHz clock which can be multipled up in the PLL to 60MHz. Then you can set 8 into USR_UCSR (the BRG register) to get 234'375kHz or 7 to get 267'857 MHz.

4. I don't know the RTC at the moment so won't attempt a response.

5 - is it possible to add a serial (spi) flash ram ?

- The chip has a QSPI module and so this is possible. I haven't done it with the 52233 but have no doubts since it works on other and much less powerful freescale devices which I have done it on.

See also the following forum posting: http://forums.freescale.com/freescale/board/message?board.id=CFCOMM&message.id=274
If you are interested in the uTasker (it is free for non-commerical use) just contact me. It includes an operating system TCP/IP stack running on the M5223X, has UART support on the three interfaces and CAN support. It also has SPI FLASH file system support for the NE64 which can probably be ported to the Coldfire quite easily. See the on-line demos to play with a live demo project.

Regards

Mark Butcher
www.mjbc.ch