how does I2Cobj work when handeling a ds1624

darkxceed · 2007-01-09 07:25

Hello people,

I am new to I2C with the propeller chip.
Now I want to read the temp of the ds1624(which is different than the ds1620).

The commandos have to be:
Start
%10010000
$AC
$00
Stop

Start
%10010000
$EE
Stop

Start
%10010000
$AA
Start
%10010001
RX··············· <receive temp reading 2 bytes long
Stop

There are ofcourse ACK after every byte that is send and·NACK after every byte that is received

How do I handle the I2Cobj.spin because I don't get it really.
I want to keep it as simple as those commando's, and no extra's like checking if there an error.

Best regards,
Bart Veenstra

Javalin · 2007-01-09 13:49

Have you read the i2cDemo.spin and i2cObject.spin comments/documentation within the example code? Also I suspect the DS1621 example will help you.

James

darkxceed · 2007-01-09 15:00

I want to do it with low level code like the funktions :
PUB i2cStop
PUB i2cStart
PUB i2cWrite(i2cData, i2cBits) : ackbit
PUB i2cRead(ackbit) : i2cData

But I dont know how to use it.
Should my code be like below

i2cObject.i2cStart
i2cObject.i2cWrite(%10010000, 8)
i2cObject.i2cWrite($AC, 8)
i2cObject.i2cWrite($00, 8)
i2cObject.i2cStop

if I want to send:

Start
%10010000
$AC
$00
Stop

to adres 4 for example.

Maybe some one help me a little bit, don't need much help.

Javalin · 2007-01-09 16:02

Hi,

You need to read the product datasheet, you seem to be missing some·steps from the communication.

The manual is here http://datasheets.maxim-ic.com/en/ds/DS1624.pdf

You really need to look at the DS1621 example as, from a brief look at the ds1624 datasheet, the two products protocols·should be nearly identitical.

James

Litefire · 2007-01-09 22:39

do you need to submit any data to the $EE address during the second command (not even a 0/1 to tell it what to do?). do you simply need to access the register?

~~Brian

Litefire · 2007-01-09 22:47

con
  _clkmode = xtal1 + pll16x       
  _xinfreq = 5_000_000

  deviceaddress = %10010000

  
obj
  i2c : "i2cobject"
  
pub start (sda, scl)
  i2c.start
  i2c.init(sda, scl, FALSE)                                        'leave at false if you have pull-up resistors, switch to TRUE to drive pins from prop (not reccomended)

pub command1 : success                                             'sends first command
  success := i2c.writelocation (deviceaddress, $AC, $00, 8, 8)     'sends device's address, then the register, then the data.  8 address bits, 8 data bits
                                                                   'saves acknowledge bit from device to "success"
  return success

pub command 2 : success
  success := i2c.writelocation(deviceaddress, $EE, "command here", 8, 8)
  return success

pub command2_alt   'use if no data is to be sent to $EE
  i2c.i2cstart                                                     'starts i2c 
  i2c.i2cwrite (deviceaddress, 8)                                  'sends device address
  i2c.i2cwrite ($EE, 8)                                            'sends register address
  i2c.i2cstop                                                      'stops i2c

pub read1 : readdata
  readdata := i2c.readlocation (deviceaddress, $AA, 8, 16)         'reads 2 bytes from register $AA (8 address bits, 2 bytes at 8 bits each = 16 data bits)
  return readdata

try that. make sure you have pullups on your data and clock lines. it needs i2cobject.spin to be in the same folder (obviously).

good luck!

darkxceed · 2007-01-10 07:01

Yes I looked at the datasheet and this is what there has to be done:

Start,%10010000,ACK,$AC,ACK,$00,ACK,Stop <==configuration register. 1shot

Start,%10010000,ACK,$EE,ACK,Stop <==Start convert.

Start,%10010000,ACK,$AA,ACK,Start,%10010001,ACK,Receivebyte,ACK,Receivebyte,NACK,Stop <==get 2 byte data

the last ACK and NACK must send from master to slave.
The ds1624 is connected to the prop with 2x 4k6 pull-up and 100Ohm resistor in serie to the prop output 28(SCL),29(SDA), the eeprom is also connected there for the propsoftware.

con
_clkmode = xtal1 + pll16x
_xinfreq = 5_000_000

deviceaddress = %10010000

obj
i2c : "i2cobject"

pub start (sda, scl)
i2c.start
i2c.init(sda, scl, FALSE)

pub Config : success························································· 'sends first command
success := i2c.writelocation (deviceaddress, $AC, $00, 8, 8)·····'sends device's address, then the register, then the data. 8 address bits, 8 data bits
return success

pub Convert····································································· 'use if no data is to be sent to $EE
i2c.i2cstart······································································ 'starts i2c
i2c.i2cwrite (deviceaddress, 8)············································· 'sends device address
i2c.i2cwrite ($EE, 8)··························································· 'sends convert prot.
i2c.i2cstop········································································'stops i2c

pub read1 : readdata
readdata := i2c.readlocation (deviceaddress, $AA, 8, 16)······· ··'reads 2 bytes from register $AA (8 address bits, 2 bytes at 8 bits each = 16 data bits)
return readdata

Post Edited (darkxceed) : 1/10/2007 7:05:58 AM GMT

darkxceed · 2007-01-10 10:29

Javalin said...
Hi,

You need to read the product datasheet, you seem to be missing some·steps from the communication.

The manual is here http://datasheets.maxim-ic.com/en/ds/DS1624.pdf

You really need to look at the DS1621 example as, from a brief look at the ds1624 datasheet, the two products protocols·should be nearly identitical.

James

I looked at the exmaple yes, and got it working.
But I don't know how to get the second byte of·temperatuur.
This byte contains the precision values lower than 1degree.

pub·read1·:·readdata
··readdata·:=·i2c.readlocation·(deviceaddress,·$AA,·8,·16)·········'reads·2·bytes·from·register·$AA·(8·address·bits,·2·bytes·at·8·bits·each·=·16·data·bits)
··return·readdata

In the upper syntax I set it to 16 to read 2 bytes but the second byte stays %00000000

If I have the second byte I than can manipulate is because only the last 5 bits contains a·measure value.
In total the tempreading is 13bits long.

If I try it in low level code I maybe understand it more.

how does I2Cobj work when handeling a ds1624

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