Diozero for waveshare ads1263 ADC

[qzic]

I'd like to extend diozero to work with this Raspberry Hat. It has a standard SPI pin assignment except for cs which is BCM 22. I'm fairly comfortable programming in Java but not an expert. Could someone give me an idea where to start. I expect I need to define a class for the device implementing the MpcAdc interface. Is there an existing class I could mimic/copy/modify? Any help would be appreciated. I scanned the core source code and have a rough idea but would rather not go down the wrong path.

[mattjlewis]

Hi. The ADS112C04 and the simpler ADS1015 / ADS1115 would be good references.

My starting points would always be the datasheet along with existing implementations for reference, e.g. this one.

[qzic]

I did look at those devices but there are references to I2C so I figured they were not usable for the SPI interface. I guess I need to look closer.

[qzic]

Those two devices hace I2C interfaces. The ADS1263 has an SPI interface. Are there any SPI interface devices in the library?

[mattjlewis]

Yes, there are also a few devices that support both SPI and I2C, e.g. MCP23x17, BMx280, the SSD OLEDs.

[qzic]

I did a tiny test and got a failure. If you see the problem, please let me know what's wrong. I suspect I'm not creating spi properly.

        logger.info("**************** SPI Test **********************");

        try (SpiDeviceInterface spi = SpiDevice.builder(0)
                .setChipSelect(22)
                .setFrequency(2_000_000)
                .setClockMode(SpiClockMode.MODE_0)
                .build()) {

            // Send some data  0x00 is ID register
            byte[] dataToSend = new byte[]{(byte) 0x00, 0x00};
            byte[] response = spi.writeAndRead(dataToSend);

            System.out.println("Received: " + bytesToHex(response));
        }

Output

INFO - **************** SPI Test **********************
Exception in thread "main" com.diozero.api.RuntimeIOException: Error in spiTransfer(), response: -1
	at com.diozero.internal.provider.builtin.spi.NativeSpiDevice.writeAndRead(NativeSpiDevice.java:108)
	at com.diozero.internal.provider.builtin.spi.NativeSpiDevice.writeAndRead(NativeSpiDevice.java:101)
	at com.diozero.internal.provider.builtin.DefaultNativeSpiDevice.writeAndRead(DefaultNativeSpiDevice.java:81)
	at com.diozero.api.SpiDevice.writeAndRead(SpiDevice.java:218)
	at ca.qzic.ads_test_spi.Main.main(Main.java:106)
open failed: No such file or directorySPI message transfer failed: Bad file descriptor

[qzic]

I also tried initializing spi with this but same problem

SpiDevice spi = new SpiDevice(0, 22, SpiConstants.DEFAULT_SPI_CLOCK_FREQUENCY,SpiConstants.DEFAULT_SPI_CLOCK_MODE, SpiConstants.DEFAULT_LSB_FIRST);

[qzic]

/dev/spidev0.0 and /dev/spidev0.1 exist and i have r/w access

[qzic]

The following does not cause an error but the bytes returned are both 0; It should be non xero the chipID. The second argument is supposed to be the BCM chip select pin so maybe because it 0, the write is not even attempted.

        logger.info("**************** SPI Test **********************");
        SpiDevice spi = new SpiDevice(0, 0, SpiConstants.DEFAULT_SPI_CLOCK_FREQUENCY,SpiConstants.DEFAULT_SPI_CLOCK_MODE, SpiConstants.DEFAULT_LSB_FIRST);
                    // Send some data
            byte[] dataToSend = new byte[]{(byte) 0x00,0x00 };
            spi.write(dataToSend);
            byte[] response = spi.writeAndRead(dataToSend);
            System.out.println("Received: " + bytesToHex(response));

output

INFO - **************** SPI Test **********************
Received: 00 00 

[qzic]

OK, I realized I had forgotten to enable chip select before spi.write. It still results in the same error but here is my current simple code.
I went through your source code but could not see where the error is. I checked that pigpiod was running and tried running as root also.
Is there any actual working SPI example in java? I don't have any idea how to go further.

    static private DigitalOutputDevice csPin;
    public static void main(String args[]) throws InterruptedException {
        csPin = new DigitalOutputDevice(22, true, false);
        csPin.setValue(true);
        logger.info("**************** SPI Test **********************");
        SpiDevice spi = new SpiDevice(0,22); //, SpiConstants.DEFAULT_SPI_CLOCK_FREQUENCY,SpiConstants.DEFAULT_SPI_CLOCK_MODE, SpiConstants.DEFAULT_LSB_FIRST);
            // Get chip ID
            byte[] dataToSend = new byte[]{(byte) 0x20, 0x00};
            csPin.setValue(false);
            byte[] response = spi.writeAndRead(dataToSend);
            csPin.setValue(true);
            System.out.println("Received: " + bytesToHex(response));
    }

Output

INFO - **************** SPI Test **********************
Exception in thread "main" com.diozero.api.RuntimeIOException: Error in spiTransfer(), response: -1
	at com.diozero.internal.provider.builtin.spi.NativeSpiDevice.writeAndRead(NativeSpiDevice.java:108)
	at com.diozero.internal.provider.builtin.spi.NativeSpiDevice.writeAndRead(NativeSpiDevice.java:101)
	at com.diozero.internal.provider.builtin.DefaultNativeSpiDevice.writeAndRead(DefaultNativeSpiDevice.java:81)
	at com.diozero.api.SpiDevice.writeAndRead(SpiDevice.java:218)
	at ca.qzic.ads_test_spi.Main.main(Main.java:105)
open failed: No such file or directorySPI message transfer failed: Bad file descriptor

[qzic]

In NativeSpiDevice the statement
String spidev = "/dev/spidev" + controller + "." + chipSelect;
fails with Chip Select 22 but not with 0 or 1

This explains why
pi@RPi-3-1:~ $ ll /dev/spi*
crw-rw---- 1 root spi 153, 0 Jun 13 16:11 /dev/spidev0.0
crw-rw---- 1 root spi 153, 1 Jun 13 16:11 /dev/spidev0.1

So the chipSelect arg is improperly named. I think it probably should be port number.

I still get 0x00, 0x00 as a response which is incorrect

[mattjlewis]

I understand the confusion - you assumed you needed to pass the BCM GPIO number for the chip select pin.

The API naming in diozero was based on a standard definition of a SPI device:

• Boards often support multiple SPI controllers (hence the controller parameter name)
• A single SPI controller can support multiple "peripheral devices" as determined by the "Chip Select" number

diozero delegates all SPI control to the kernel - hence diozero is oblivious to SPI device physical CS / MOSI / MISO / SCLK pins.

I can review the API Javadoc to make this clearer.

[qzic]

Well now that that's sorted out, I'm able to write and read from the SPI port. Now it's up to me to figure out what's wrong with my protocol.

[qzic]

FYI, After much digging, it works!. I had taken an ADS1263 python demo program and used S/W Architect GPT to translate to java. Never expected it to work but save a lot of time with constant definition etc. The key problem was that I was also getting a 0x00 on a data read. Turns out my method to ask for data was writing to the wrong register. After that everything fell into place. I noticed in the link https://en.wikipedia.org/wiki/Serial_Peripheral_Interface is calls the spi chip select Slave Select (SS). I'm naming it as such in my code.
Thanks for your help. After I cleanup the code a bit I'll upload to github and send you a link.

[qzic]

So here is my ADS1263 demo project using diozero. It is a Netbeans Maven project.
It should only need the RPi IP address added in the pom.xml. Then a simple Run will build, download, run the program.
https://github.com/qzic/ADS1263_Demo