ams AS5048 14-bit Rotary Position Sensor with Digital Angle and PWM

Output

Product Information

The AS5048 is a 14-bit rotary position sensor with digital angle (interface) and PWM output. It is designed by ams OSRAM Group and published by Arrow.com. The sensor is used to measure the position of a rotating object and provides accurate angle measurements.
The AS5048 adapter board is a circuit that allows for easy testing and evaluation of the AS5048 sensor without the need for building a separate test fixture or PCB. The adapter board can be attached to a microcontroller or the AS5048-Demoboard as an external device.

Board Description
The AS5048 Adapterboard features an interface type A (SPI) or B (I2C), 4 x 2.6mm mounting holes, and a P1 connector. It provides a convenient way to connect and interact with the AS5048 sensor.

Mounting Instructions

To mount the AS5048 adapter board, follow these steps:

1. Place a diametric magnet over or under the AS5048 position sensor.
2. Ensure that the magnet is centered on the middle of the package with a tolerance of 0.5mm.
3. Maintain an airgap between the magnet and the encoder casing in the range of 0.5mm to 2mm.
4. Use a non-ferromagnetic material such as brass, copper,aluminum, or stainless steel for the magnet holder.

Following these instructions will ensure proper functioning of the AS5048 adapter board and accurate position measurements.

Revision History

General Description

The AS5048 is an easy to use 360° angle position sensor with a 14-bit high resolution output. To measure the angle, only a simple two-pole magnet, rotating over the center of the chip, is required.
The magnet may be placed above or below the IC. This is shown in Figure 1.

Figure 1: Magnetic Position Sensor AS5048 + Magnet

The AS5048 adapter board
The AS5048 adapter board is a simple circuit allowing test and evaluation of the AS5048 magnetic position sensor quickly without building a test fixture or PCB.

Board description
The AS5048 Adapterboard is a simple circuit allowing test and evaluation of the AS5048 rotary encoder quickly without building a test fixture or PCB.
The PCB can be attached to a microcontroller or to the AS5048- Demoboard as external device.

Figure 2: AS5048 Adapterboard

Mounting the AS5048 adapter board
A diametric magnet must be placed over on under the AS5048 position sensor, and should be centered on the middle of the package with a tolerance of 0.5mm.
The airgap between the magnet and the encoder casing should be maintained in the range 0.5mm~2mm. The magnet holder must not be ferromagnetic. Materials as brass, copper, aluminum, stainless steel are the best choices to make this part.

Figure 3: AS5048 – AB – mounting and dimension

AS5048 adapter board and pinout

Figure 4: AS5048 adapter board connectors and encoder pinout

Table 1: Pin description

Pin# Board| Pin# AS5 048| Symbol Board| ****

Description

---|---|---|---
P1 – 1| 13| GND| Supply ground
P1 – 2| 3| A2/MISO| SPI master in/slave out; shared with I2C address selection pin 2
P1 – 3| 4| A1/MOSI| SPI master out/slave in; shared with I2C address selection pin 1
P1 – 4| 2| SCL/SCK| SPI clock input; shared with I2C clock input
P1 – 5| 1| SDA/CSn| SPI chip select-active low; shared with I2C data pin
P1 – 6| 14| PWM| Pulse width modulation output

P1 – 7

| ****

12

| ****

3.3V

| 3V-Regulator output; internally regulated from VDD. Connect to VDD for 3V supply voltage
P1 – 8| 11| 5V| Supply voltage

Operation cases

The most complete and accurate solution for a MCU to read the angle of a magnet is the SPI interface.

One Device SPI mode, unidirectional – 3 wire
The AS5048-AB can be directly connected to an industry standard SPI port of a microcontroller. The minimum connection requirement for unidirectional communication (angle + alarm values reading) between the microcontroller and the AS5048 are MISO, SCK, SS/.
The angle will be read at each 16-bit SPI transfer. See AS5048 datasheet register table, register 3FFFh.

Figure 5: Using the SPI Interface unidirectional with a microcontroller

One device SPI mode, bidirectional – 4 wire
If other registers than only angle values have to be read, or in order to write registers into the AS5048, the signal MOSI is necessary.

Figure 6: Using the SPI Interface bidirectional with a microcontroller

Multi devices SPI Daisy chain mode
The AS5048 can be daisy chained, using 4 wires only for SPI communication.
In this configuration with n x encoders, the sequence will be processed as follow:

• MCU sets SS/ = 0

• MCU shifts n x 16-bit (e.g. READ command FFFFh) through the chain

• MCU sets SS/=1
  At that point all the n x encoders have received the READ command FFFFh.

• MCU sets SS/=0

• MCU shifts n x 16-bit (e.g. NOP command 0000h)

• MCU sets SS/=1
  At that point the n x 16-bit received on MISO are the n x angle values.

Figure 7: Multi Devices in Daisy chain mode

Firmware coding

The following source code fits the 4-Wire application
The function void spiReadData() reads/writes 4 values from the AS5048

• Send command READ AGC / Receive value unknown
• Send command READ MAG / Receive value AGC
• Send command READ Angle / Receive value MAG
• Send command NOP (no operation) / Receive value ANGLE

If a READ ANGLE only is necessary in a loop, the procedure can be reduced to one line:

• Send command READ Angle / Receive value Angle
  The function static u8 spiCalcEvenParity(ushort value) is optional, it calculates the parity bit of the 16-bit SPI stream.

/*!

• Reads out chip data via SPI interface
• This function is used to read out cordic value from chips supporting SPI
• interface.

  ---

  */

  define SPI_CMD_READ 0x4000 /*!< flag indicating read attempt when using SPI

  interface */

  define SPI_REG_AGC 0x3ffd /!< agc register when using SPI /

  define SPI_REG_MAG 0x3ffe /!< magnitude register when using SPI /

  define SPI_REG_DATA 0x3fff /!< data register when using SPI /

  define SPI_REG_CLRERR 0x1 /!< clear error register when using SPI /

void spiReadData()
{
u16 dat; // 16-bit data buffer for SPI communication
u16 magreg;
ushort angle, agcreg;
ubyte agc;
ushort value;
bit alarmHi, alarmLo;

/ Send READ AGC command. Received data is thrown away: this data comes from the precedent command (unknown)/
dat = SPI_CMD_READ | SPI_REG_AGC;
dat |= spiCalcEvenParity(dat) << 15;
spiTransfer((u8*)&dat, sizeof(u16));

/ / Send READ MAG command. Received data is the AGC value: this data comes from the precedent command (unknown)/
dat = SPI_CMD_READ | SPI_REG_MAG;
dat |= spiCalcEvenParity(dat) << 15;
spiTransfer((u8)&dat, sizeof(u16));
magreg = dat;
/ Send READ ANGLE command. Received data is the MAG value, from the precedent command /
dat = SPI_CMD_READ | SPI_REG_DATA;
dat |= spiCalcEvenParity(dat) << 15;
spiTransfer((u8)&dat, sizeof(u16));
agcreg = dat;
/ Send NOP command. Received data is the ANGLE value, from the precedent command /
dat = 0x0000; // NOP command.
spiTransfer((u8)&dat, sizeof(u16));
angle = dat >> 2;
}
if ((dat & 0x4000) || (agcreg & 0x4000) || (magreg & 0x4000))
{
/ error flag set – need to reset it /
dat = SPI_CMD_READ | SPI_REG_CLRERR;
dat |= spiCalcEvenParity(dat)<<15;
spiTransfer((u8)&dat, sizeof(u16));
}
else
{
agc = agcreg & 0xff // AGC value (0..255)
value = dat & (16384 – 31 – 1); // Angle value (0.. 16384 steps)
angle = (value 360) / 16384 // Angle value in degree
(0..359.9°)
magnitude = magreg & (16384 – 31 – 1);
alarmLo = (agcreg >> 10) & 0x1;
alarmHi = (agcreg >> 11) & 0x1;
}
}
/!

• Calculate even parity of a 16 bit unsigned integer
• This function is used by the SPI interface to calculate the even parity
• of the data which will be sent via SPI to the encoder.
• \param[in] value : 16 bit unsigned integer whose parity shall be calculated
• \return : Even parity

• ---

  /
  static u8 spiCalcEvenParity(ushort value)
  {
  u8 cnt = 0;
  u8 i;
  for (i = 0; i < 16; i++)
  {
  if (value & 0x1)
  {
  cnt++;
  }
  value >>= 1;
  }
  return cnt & 0x1;
  }
  /!

  ---

• Calculate even parity of a 16 bit unsigned integer
• This function is used by the SPI interface to calculate the even parity
• of the data which will be sent via SPI to the encoder.
• \param[in] value : 16 bit unsigned integer whose parity shall be calculated
• \return : Even parity

• ---

  */
  static u8 spiCalcEvenParity(ushort value)
  {
  u8 cnt = 0;
  u8 i;
  for (i = 0; i < 16; i++)
  {
  if (value & 0x1)
  {
  cnt++;
  }
  value >>= 1;
  }
  return cnt & 0x1;
  }

AS5048-AB-Hardware

Following the schematic and layout of the Adapterboard can be found.

AS5048-AB-1.1 Schematics

Figure 8: AS5048-AB-1.1 adapterboard schematics

AS5048 – AB – 1.1 PCB layout

Figure 9: AS5048-AB-1.1 adapter board layout

Copyright
Copyright ams AG, Tobelbader Strasse 30, 8141 Unterpremstätten, Austria- Europe. Trademarks Registered. All rights reserved. The material herein may not be reproduced, adapted, merged,translated, stored, or used without the prior written consent of the copyright owner.

Disclaimer
Devices sold by ams AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. ams AG makes no warranty, express, statutory, implied, or by description regarding the information set forth herein. ams AG reserves the right to change specifications and prices at any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with ams AG for current information. This product is intended for use in commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high- reliability applications, such as military, medical life-support or life- sustaining equipment are specifically not recommended without additional processing by ams AG for each application. This Product is provided by ams “AS IS” and any express or implied
warranties, including, but not limited to the implied warranties of merchantability and fitness for a particular purpose are disclaimed.
ams AG shall not be liable to recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect,special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of ams AG rendering of technical or other services.

Contact Information
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ams AG
Tobelbader Strasse 30
8141 Unterpremstaetten
Austria
T. +43 (0) 3136 500 0
For Sales Offices, Distributors and Representatives, please visit:
http://www.ams.com/contact

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