Hello everyone
I want to create the code for the DAC80501 but it is not clear to me the data package I have to send.
I seem to have understood that the data packet is 24bit total but I still can't get the information together.
The andress bytes are 8bit but then talk about command bits which are 4 and make 12.
Where do I put the other 16bit?
thanks a lot
ms
Massimo,
I'll admit that the datasheet is a little confusing. It was written to show the communication for both I2C and SPI with the data and command structure.
If you're using SPI communications, you do not use the addresses for Table 2. The section for the DACx0501 Address Byte (described in 8.5.1.2.2.1) is used for the I2C address. To communicate with the DACx0501, you use the /SYNC pin similar to a chip select pin.
Using SPI communications, you only need the 24 bit transfer for a valid write sequence taken from Figure 58:
After that, you use the command byte for the first 8 bits of the 24 bit transfer, as you see in Table 4:
And then you follow that with the data bytes from Table 5 (note that B19-B16 from the command byte are shown in the table below):
The bits from Table 4 and Table 5 total 24 bits and that aligns with the 24 bits that you see in the valid write you see in Figure 58.
If you use I2C communication, you need to use the I2C address from the values in Table 2. Then you follow the I2C communication byte by byte. First you send the command byte, then the MSB data byte, then the LSB data byte.
Joseph Wu
Massimo,
You are correct that the first four bits then become zero. As an example, if you want to set the output DAC to half scale you would write 8000h to the DAC DATA register. To access the register, you send 08h for the command bits. For the sequence, you would send 08 80 00 for the 24-bit transfer.
The data lines would look like this:
For this mode of SPI, the /SYNC acts as the chip select, and data is clocked into the device on the falling edge of SCLK.
Joseph Wu
Hi, before asking for help again I did some tests.
I prepared the 3 bytes 0x08h 80h and 00h then I altered the last bits to read any voltage on the DAC output.
I have no tension.
I wondered that there are two other 3byte groups to configure the DAC.
With the data sheet table I built this set of 9 bytes that I found on the net.
I haven't solved anything.
On the oscilloscope it looks correct.
Where am I wrong?
Thanks so much for the replies
ms
CS,SCL,SDIN
1) 0x05 00 0A // Soft-ResetDelay 200ms
2) 0x04 01 00 // RefDiv 2, Gain 1 -> 1.25V max. Output
3) 0x08 43 21 // some DAC code, ~ 328mV
Massimo,
The original posts that you showed are incorrect because each set of 3 bytes should be separated by a /SYNC pulse. Taking your original plots, this is how they should look (inserted /SYNC pulses).
However, you most recent post shows that you correctly have the each of the three bytes separated by the /SYNC pulse (although you only show two different 3 byte communications.
So is this what you see on the oscilloscope? What you're sending looks like TINA simulations, not a real scope plot or output from a digital analyzer. Can you get a real read from a four channel channel scope or logic analyzer?
I've gotten your schematic and I'm looking through it. There's quite a bit to look at, and it may take some time to review it.
Joseph Wu
Hi Joseph
If you prefer, I'll make you the simplified connection diagram.
In theory, the development board should be transparent
and the pins of the DAC80501 are connected to the pins of the Pic 18f45k22 in the following way: RE0 = CS, SCLK = RC3, SDI = RC5.
I have industrial Tina 12 and Tina Lab2 the measure is real but I don't know how reliable it is.
I am sending you the lines of code I wrote to test with mikroC pro if it can be useful.
Thanks again for the help.
ms
/*DAC 16bit convertitore DAC80501
Quarzo 8 Mhz PIC 18f45k22 */
//SPI
sbit Chip_Select at RE0_bit;//CS selezione CHIP
sbit Chip_Select_Direction at TRISE0_bit;
void Init() //DAC80501
{
// Initialize variables
// Init SPI
SPI1_Init_Advanced(_SPI_MASTER_OSC_DIV64, // Initialize PIC as master
_SPI_DATA_SAMPLE_MIDDLE, // _SPI_DATA_SAMPLE_MIDDLE,
_SPI_CLK_IDLE_LOW,
_SPI_HIGH_2_LOW );
Chip_Select_Direction= 0; // ClearBit(TRISC,0)
Chip_Select= 1; // SetBit(PORTC,0)
}//**********************************************************************************
void main (){
ANSELC=0;
Init();
do{
Chip_Select= 1;
Chip_Select= 0;
SPI1_Write(0x05);
SPI1_Write(0x00);
SPI1_Write(0x0A);
Chip_Select= 1;
Chip_Select= 0;
SPI1_Write(0x04);
SPI1_Write(0x01);
SPI1_Write(0x00);
Chip_Select= 1;
Chip_Select= 0;
SPI1_Write(0x08);
SPI1_Write(0x43);
SPI1_Write(0x21);
Chip_Select= 1;
}
while(1);
}
