Sending 16Bit serial Data

Dr.Nokill · Joined: 18 Jul 2004 Posts: 1

Hello,

i need to controll a chip with the help of a microcontroller. I have to send serial data to this chip.
I have to set a pin EN to LOW state and when the CLOCK goes HIGH I have to send the MSB. on every rising edge of the CLOCK i have to send another Bit to the chip while EN stays LOW, after 16bit the EN is set to high.

With the standard SPI $serialoutput datalength is 8Bit.
How can I set it to 16Bit, or how can i send syncron 16 bit serial data to an external device.

(this is my first trie with µC...)

Thank you for your help

DJD XTREEM · Joined: 24 Jun 2004 Posts: 190 Location: 127.0.0.1

I need to send an 14 or 16 bit HEX code to a device::

For example (this code is in HEX): 86 00 00 04 00 01 0C
But also this one:: 87 00 00 05 08 40 09 5D

This all have to be acivated on key presses..

The key systems i'sn't the problem.. But how do i have to send those codes?? Confused

Need a quick solution.. Because i need it tommorow to run Shocked

So please help...

Frankeman · Joined: 11 Aug 2004 Posts: 945 Location: the Netherlands

@ Dr.Nokill

Make you own SPI, its not so hard.
Put your bit data in two bytes, then assign bit by bit the bit value to a portpin.
Psuedo code:

Set a portpin low 'enable - look at the reset statement

Set a portpin high 'clock - look at the set statement
Set a portpin to the value of the bit index of a byte 'data - portb.2 = var1.0
Set the clockpin low
proberly wait for a while 'look at the waitms statement

Set a portpin high
Set a portpin to the value of the bit index of a byte 'data - portb.2 = var1.1
Set the clockpin low
proberly wait for a while

repeat this 16 times

Set the enablepin high

Frank.

ps: if this don't work you have to control the portpins at the same time, in this case you must combine the clock and the data pin in a byte and control the port with the byte you just have made.

Frankeman · Joined: 11 Aug 2004 Posts: 945 Location: the Netherlands

@ DJD

You don't send BITS but BYTES, in your case 7 or 8 bytes.
So you can use the normal SPI routines.
Put all your variabele in an array and call SPIOUT with the number of bytes you want to send.

dim A(10) as byte
Spiout A(1) , 8
Spiout A(1) , 7

DJD XTREEM · Joined: 24 Jun 2004 Posts: 190 Location: 127.0.0.1

Well i did some try's today..

But have some problems with the HEX codes.. Because when i use a spy cable in combination with RSlook232 (rs232 spy software) the code that is set on de serial line isn't the hex code that i gave to send..

And some other try's to send the code on different ways by bascom resulting in compiler errors.. Tripple checked the help files of bascom but can't get those codes on the serial line..

Anyone sugestions??

Frankeman · Joined: 11 Aug 2004 Posts: 945 Location: the Netherlands

Hi,

When you use the hardeware SPI it is possible to set what bit is send first MSB or LSB.
Maybe the bytes are send in reverse, this is easy to check for you.
If not fill an array with known values like 1, 2, 3, 4, 5 and see what happens if you send these.
Another possibility is that you confuse HEX en DECIMAL.

Frank.

DJD XTREEM · Joined: 24 Jun 2004 Posts: 190 Location: 127.0.0.1

Well i tryed some things again..
But with no luck..
The only thing that it has to do is send some HEX strings over the serial line..

for example when i use this to send a code::

philm · Joined: 14 Jul 2004 Posts: 138 Location: Australia

Frankeman · Joined: 11 Aug 2004 Posts: 945 Location: the Netherlands

Normaly you send values not hex codes.
The little example shows how to do this.

albertsm · Joined: 09 Apr 2004 Posts: 5319 Location: Holland

Yes, that explains it well. But to make sure here is some more info.
When we have a variable named B, and it is of the type BYTE, it can hold values from 0-255.
Ok, let say we assign it value of 16 (dec). This is :
16 (dec)
10 (hex)
0001 0000 (bin)
this is just different notation. the value remains the same.

Now when we send this value to the TX pin, we can sent it in different ways.
When we like to send the binary value, we need to sent just 1 byte : PRINT chr(b);
The ; we use so no CR+LF is added.

When we like to send it as a number (dec) we use : PRINT B ;
This will convert the value B into "16" and will thus send a byte with value 49 and 54. (ascii value of "1" = 49)

Now when we want to send as HEX, we use : PRINT HEX(b) ;
This will convert the byte into "10" and will send 2 bytes again.

So there is a huge differenc e between sending BINARY data (with CHR or PRINTBIN) and sending the ASCII representation of the value.