Interfacing 8051 UART to I2C slave

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Read-Only Author Matt S Posted 26-Feb-2003 05:08 GMT Toolset C51	Interfacing 8051 UART to I2C slave Matt S Does anyone have any ideas on interfacing the standard 8051 UART in mode 0 to interface to an I2C slave? I was thinking of writing the address of the slave, then shifting the acknowledge back in immediatley after. Any feedback would be appreciated. Matt

Read-Only Author erik malund Posted 26-Feb-2003 14:01 GMT Toolset C51	RE: Interfacing 8051 UART to I2C slave erik malund You can not drive IIC with an UART. Erik

Read-Only Author Geert Vancompernolle Posted 26-Feb-2003 18:00 GMT Toolset C51	RE: Interfacing 8051 UART to I2C slave Geert Vancompernolle The only way you can have I2c communication, is when you yourself are manipulating some pins of some port (eg. P1.6 and P1.7). I suggest not to use pins that have already a double functionality (like for instance P3.0 and P3.1, which can be used for UART communication too). Unless your device has a hardware I2c controller on board, you should write the I2c protocol yourself (which isn't that difficult).

Read-Only Author erik malund Posted 26-Feb-2003 18:10 GMT Toolset C51	RE: Interfacing 8051 UART to I2C slave erik malund you should write the I2c protocol handler yourself or download the code linked to in one of the many Philips appnotes. Erik

Read-Only Author Matt Stoll Posted 26-Feb-2003 21:21 GMT Toolset C51	RE: Interfacing 8051 UART to I2C slave Matt Stoll Thanks I was just wondering if it was possible Matt

Read-Only Author Drew Davis Posted 27-Feb-2003 00:52 GMT Toolset C51	RE: Interfacing 8051 UART to I2C slave Drew Davis One problem with using the UART is that I2C bus is synchronous; you have a clock for every data bit to tell you when the bit is valid. A UART is asynchronous (hence the 'A'); there's no extra clock line, and you time from the edge of the start bit, hoping that the transmit and receive clocks are close enough that you don't wander "out of the bit" and sample the wrong value. Those start and stop bits would themselves be a problem, since they shouldn't appear in an I2C transfer. Another problem is that the I2C data line is bidirectional. You read and write with the same data line. A UART has separate transmit and receive pins, and you'd run into interesting problems with who drives the line at what time. Both interfaces are serial, but they're not really much alike.

Read-Only Author Mingyong Zhou Posted 18-Aug-2004 03:09 GMT Toolset C51	RE: Interfacing 8051 UART to I2C slave Mingyong Zhou We have one project which needs the communication between UART (serial port) and I2c using 8051. Any tools , software in the market one can purchase? Sound like the translation bewteen UART and I2C is not that easy from this technical forum discussion. Any suggestion will be appreciated. zhou.ming.yong@philips.com tel: +65 6 882 3085

Read-Only Author Russell Bull Posted 18-Aug-2004 04:52 GMT Toolset C51	RE: Interfacing 8051 UART to I2C slave Russell Bull It is all too easy to get confused with this discussion. The initial thrust of this discussion was coonecting the serial port to the I2C device - and for the abovementioned reasons it will not work. Now, if you want to received commands and data via the serial port (uart) then send them to an I2C device, that is possible and fairly easy. There is plenty of code around detailing how to ise the uart and implementing an I2C master, all you need to do is come up with a method of connecting the two via software. Obviously this can depend of what sort of I2C devices you wish to talk to. If it is a I2C real time clock chip, you would want to read and write the time, if it is a eeprom, then you want to read and write bytes. What do you want to do?

Read-Only Author Mingyong Zhou Posted 19-Aug-2004 03:08 GMT Toolset C51	Interfacing 8051 UART to I2C with I2C as master Mingyong Zhou I would appreciate if anybody can provide software C samples to use I2C as master to communicate and control UART, because of the time deadline. Any reference to website or resources appreciated.

Read-Only Author Russell Bull Posted 19-Aug-2004 03:22 GMT Toolset C51	RE: Interfacing 8051 UART to I2C with I2C as master Russell Bull 'I2C master to communicate and control uart' I think you need to explain exactly what you want to do. As mentioned previously, you don't connect I2C to uart! If you want a uart with an I2C interface, Maxim have a device that does this. You would use this device when you want to add more serial ports to your microcontroller via the I2C . Is this what you want to do? Gong Xi Fat Choi!

Read-Only Author Andy Neil Posted 19-Aug-2004 07:17 GMT Toolset C51	RE: Interfacing 8051 UART to I2C with I2C as master Andy Neil "I would appreciate if anybody can provide software C samples to use I2C ..." I note that you gave your e-mail address as: zhou.ming.yong@philips.com Surely someone at Philips should have access to all the I2C support one could ever wish for...?!

Read-Only Author erik malund Posted 19-Aug-2004 13:40 GMT Toolset C51	RE: Interfacing 8051 UART to I2C with I2C as master erik malund "I would appreciate if anybody can provide software C samples to use I2C ..." I note that you gave your e-mail address as: zhou.ming.yong@philips.com Is'nt it amazing. Software for IIC is in several appnotes at the Philips website http://www.semiconductors.philips.com/products/all_appnotes/ Erik

Read-Only Author Oleg Sergeev Posted 20-Aug-2004 06:52 GMT Toolset C51	RE: Interfacing 8051 UART to I2C slave Oleg Sergeev hi, A UART is asynchronous (hence the 'A'); there's no extra clock line, Not always. Read some more about UART mode 0 (shift register mode). In this mode, UART provides separate data line and clock line. A UART has separate transmit and receive pins, and you'd run into interesting problems with who drives the line at what time Again - not always. In mode 0 UART provides bidirectional line RX for both receive and transmit. Line TX is used for clock out only. Regards, Oleg

Read-Only Author Andy Neil Posted 20-Aug-2004 07:01 GMT Toolset C51	RE: Interfacing 8051 UART to I2C slave Andy Neil "Not always. Read some more about UART mode 0 (shift register mode). In this mode, UART provides separate data line and clock line." To be pedantic, we could say that the 8051's Serial Interface is not acting as a UART in this mode... ;-)

Read-Only Author Michael Baldischweiler Posted 21-Aug-2004 16:26 GMT Toolset C51	RE: Interfacing 8051 UART to I2C slave Michael Baldischweiler And the ACK-Flag ? How can you test this ? per software ? seperate 9 clock ? Not really !

Read-Only Author Desmond Yeo Posted 7-Oct-2005 08:43 GMT Toolset C51	RE: Interfacing 8051 UART to I2C slave Desmond Yeo there is a Philips IC that bridge UART to I2C. Pls send me your e-mail address.

Read-Only Author Andrew Neil Posted 7-Oct-2005 23:02 GMT Toolset C51	Async to I2C "bridge" Andrew Neil "there is a Philips IC that bridge UART to I2C." Maxim also do such things - as has already been mentioned! Most likely there are others, too. Of course, you could easily implement such a thing with just about any microcontroller - whether you use dedicated hardware UART and I2C peripherals, or implement either or both in software ("bit-banging")...

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