• AD7291

• EVAL-AD7291SDZ

The AD7291 is a 12-bit, low power, 8-channel, successive approximation analog-to-digital converter (ADC) with an internal temperature sensor.

The part operates from a single 3.3 V power supply and features an I2C-compatible interface. The part contains a 9-channel multiplexer and a track-and-hold amplifier than can handle frequencies up to 30 MHz. The device has an on-chip 2.5 V reference that can be disabled to allow the use of an external reference.

The AD7291 provides a 2-wire serial interface compatible with I2C interfaces. The I2C interface supports standard and fast I2C interface modes. The AD7291 normally remains in a partial power-down state while not converting and powers up for conversions. The conversion process can be controlled by a command mode where conversions occur across I2C write operations or an autocycle mode selected through software control.

The AD7291 includes a high accuracy band gap temperature sensor, which is monitored and digitized by the 12-bit ADC to give a resolution of 0.25°C.

The AD7291 offers a programmable sequencer, which enables the selection of a preprogrammable sequence of channels for conversion.

On-chip limit registers can be programmed with high and low limits for the conversion results; an out-of-range indicator output (ALERT) becomes active when the programmed high or low limits are violated by the conversion result. This output can be used as an interrupt.

The goal of this project (Microcontroller No-OS) is to be able to provide reference projects for lower end processors, which can't run Linux, or aren't running a specific operating system, to help those customers using microcontrollers with ADI parts. Here you can find a generic driver which can be used as a base for any microcontroller platform and also specific drivers for Renesas platforms.

HW Platform(s):

• Renesas Demo Kit for RL78G13 (Renesas)

The driver contains two parts:

• The driver for the AD7291 part, which may be used, without modifications, with any microcontroller.
• The Communication Driver, where the specific communication functions for the desired type of processor and communication protocol have to be implemented. This driver implements the communication with the device and hides the actual details of the communication protocol to the ADI driver.

The Communication Driver has a standard interface, so the AD7291 driver can be used exactly as it is provided.

There are three functions which are called by the AD7291 driver:

• I2C_Init() – initializes the communication peripheral.
• I2C_Write() – writes data to the device.
• I2C_Read() – reads data from the device.

The following functions are implemented in this version of AD7291 driver:

This section contains a description of the steps required to run the AD7291 demonstration project on a Renesas RL78G13 platform.

• Renesas Demo Kit for RL78G13 (Renesas)
• EVAL-AD7291SDZ(ADI)

• IAR Embedded Workbench for Renesas RL78 Kickstart
• Applilet4 for RL78G13

An EVAL-AD7291SDZ has to be interfaced with the Renesas Demonstration Kit (RDK) for RL78G13:

  EVAL-AD7291SDZ test point T_SCLK         → YRDKRL78G13 J9 connector Pin 1
  EVAL-AD7291SDZ test point TDOUT          → YRDKRL78G13 J9 connector Pin 3
  EVAL-AD7291SDZ J16 connector Pin DGND    → YRDKRL78G13 J11 connector Pin 5
  EVAL-AD7291SDZ J16 connector Pin VDRIVE  → YRDKRL78G13 J11 connector Pin 6
  EVAL-AD7291SDZ J15 connector Pin AGND    → YRDKRL78G13 J11 connector Pin 5
  EVAL-AD7291SDZ J15 connector Pin EXT_VCC → YRDKRL78G13 J11 connector Pin 6

With the Applilet3 for RL78G13 tool the following peripherals have to be configured:

Choose to generate the Transmit/receive function for the CSI10 and configure the interface with the following settings:

• Transfer mode setting: Single transfer mode
• Data length setting : 8 bits
• Transfer direction setting: MSB
• Specification of data timing: Type 1
• Transfer rate setting – Clock mode: Internal clock (master)
• Transfer rate setting – Baudrate: 1000000 (bps)
• Interrupt setting – Transfer interrupt priority (INTCSI10): Low
• Uncheck the callback functions.

Configure TM00 as an interval timer:

• Interval timer setting - Interval value(16 bits): 1 ms
• Interval timer setting - Uncheck Generates INTM00 when counting is started
• Interrupt setting - Uncheck End of timer channel 0 count, generate an interrupt (INTM00)

Disable the watchdog timer:

• Choose for the Watchdog timer operation setting: Unused option.

The reference project initializes the I2C communication peripheral and configures AD7291 to perform readings from analog inputs CH1 and CH7. The temperature is also read and displayed on the screen in degrees Celsius.

This section contains a description of the steps required to run the AD7291 demonstration project on a Renesas RX62N platform.

• Renesas Demo Kit for RX62N (Renesas)
• EVAL-AD7291SDZ(ADI)

• High-performance Embedded Workshop for RX62N family
• Renesas Peripheral Driver Library for RX62N family

An EVAL-AD7291SDZ has to be interfaced with the Renesas Demonstration Kit (RDK) for RX62N:

  EVAL-AD7291SDZ test point T_SCLK (SCL)   → YRDKRX62N J2  connector Pin 1
  EVAL-AD7291SDZ test point TDOUT (SDA)    → YRDKRX62N J2  connector Pin 3
  EVAL-AD7291SDZ J16 connector Pin DGND    → YRDKRX62N J8  connector Pin 4
  EVAL-AD7291SDZ J15 connector Pin AGND    → YRDKRX62N J8  connector Pin 4
  EVAL-AD7291SDZ J16 connector Pin VDRIVE  → YRDKRX62N J8  connector Pin 3
  EVAL-AD7291SDZ J15 connector Pin EXT_VCC → YRDKRX62N J8  connector Pin 3

The reference project initializes the I2C communication peripheral and configures AD7291 to perform readings from analog inputs CH1 and CH7. The temperature is also read and displayed on the screen in degrees Celsius.