The default I2C address is 0x4C.
There are two variants of this DAC: the 10-bit DAC6578 and the 12-bit DAC7578. The pinout is the same for both.
Power Pins
- VCC - this is the power pin. To power the board, give it the same power as the logic level of your microcontroller - e.g. for a 5V micro like Arduino, use 5V.
- VRf - this is the reference voltage pin. By default, it is tied to VCC and as a result will share the same voltage level.
- Vrf Jumper - this is the reference voltage jumper. It is located on the front of the board, to the left of the DACx578 chip. If you cut this jumper, the VRf pin is disconnected from VCC and can be connected to to any voltage between 0 and the VCC voltage level. For example, if you want a precision 4.095V reference, you'll need to cut the Vrf jumper, power with 5V to VCC, and provide 4.095V on the VRf pin.
- GND - common ground for power and logic
I2C Logic Pins
- SCL - I2C clock pin, connect to your microcontroller's I2C clock line. This pin can use 3-5V logic, and there's a 10K pullup on this pin.
- SDA - I2C data pin, connect to your microcontroller's I2C data line. This pin can use 3-5V logic, and there's a 10K pullup on this pin.
- STEMMA QT - These connectors allow you to connect to dev boards with STEMMA QT (qwiic) connectors or to other things with various associated accessories
DAC Output Pins
Along the top edge of the board are the DAC output pins. They are labeled 0-7. Each pin is connected to one of the eight channel outputs from the DACx578.
Other Pins
- LDAC - This is the load DAC pin. LDAC is used for synchronous or asynchronous updating of the DAC outputs. According to the datasheet, you should be able to toggle this pin to send the buffer to the output pins after using the write only command. However, in testing, this pin has not worked as described.
- CLR - This is the clear pin. It clears all DAC registers and buffers, replacing them with the value stored in the clear code register. The register can be set to zero-scale, mid-scale, full-scale, or disabled. The default setting of the clear code register sets the output of all DAC channels to 0V when the CLR pin is brought low.
In testing, the LDAC pin has not worked as described in the datasheet. Its believed to be a silicon bug in the DACx578.
I2C Address Jumper
On the back of the board is a three section jumper labeled AD0, directly above the DACx578 label on the board silk. This jumper allow you to chain up to 3 of these boards on the same pair of I2C clock and data pins. To do so, you solder the jumpers "closed" by connecting the two pads.
The default I2C address is 0x4C. This address is set by leaving the address pin floating. None of the jumper pads soldered closed.
If you solder the center jumper pad to the pad to its left, you connect the address pin to GND and set the I2C address to 0x48.
If you solder the center jumper pad to the pad to its right, you connect the address pin to VCC and set the I2C address to 0x4A.
The table below shows all possible addresses and the jumper positions.
Power LED and LED Jumper
- Power LED - In the upper left corner, above the STEMMA connector, on the front of the board, is the power LED, labeled on. It is a green LED.
- LED jumper - This jumper, labeled LED on the board silk, is located on the back of the board, on the right. Cut the trace on this jumper to cut power to the "on" LED.
Page last edited March 12, 2025
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