Digilent Pmod CAN Reference Manual

1300 Henley Court

Pullman, WA 99163

509.334.6306

www.store. digilent.com

Pmod CAN Reference Manual

Revised August 31, 2017
This manual applies to the Pmod CAN rev. B

SKU: 410-353

Copyright Digilent, Inc. All rights reserved.

Other product and company names mentioned may be trademarks of their respective owners.

Page 1 of 8

Overview

The Digilent Pmod CAN (Revision B) is a CAN 2.0B controller with an integrated transceiver. The
embedded Microchip MCP25625 chip connects directly to the physical CAN bus and meets automotive
requirements for high-speed (1 Mb/s), low quiescent current, electromagnetic compatibility, and electrostatic
discharge.

1 Specifications

Parameter

Min

Typical

Max

Units

Power Supply Voltage (Vcc)

2.7 5.5

V

High-Level Input Voltage (RxCAN)

2 - Vcc+1

V

Low-Level Input Voltage (RxCAN)

-0.3 - 0.15*Vcc

V

High-Level Output Voltage (TxCAN)

Vcc-0.7 - -

V

Low-Level Output Voltage (TxCAN)

- - 0.6 V Bit Frequency

14.4 - 1000

kHz

The Pmod CAN.

 Standalone CAN 2.0B controller with an

integrated CAN transceiver

 Compatible with ISO-11898-1, ISO-11898-2, and

ISO-11898-5

 Suitable for automotive applications
 Up to 1 Mb/s operation
 Up to 10 MHz SPI clock speed
 3 Transmit buffers with prioritization and abort

feature

 2 Receive buffers
 6 Filters and 2 masks with optional filtering on

the first two data bytes

 Interrupt output pin
 Standard DB9 connector for a secure connection
 Suitable for 12 V and 24 V systems
 Small PCB size for flexible designs 1.4 in x 1.8 in

(3.6 cm x 4.6 cm)

 12-pin Pmod connector with SPI interface
 Follows the Digilent Pmod Interface

Specification 1.1.0

Pmod CAN Reference Manual

Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.

Page 2 of 8

Transmitter

Min

Typical

Max

Units

Recessive Bus Output Voltage

(CANH & CANL)

2.0

0.5 Vcc

3.0

V

Dominant Output Voltage (CANH)

2.75

3.50

4.50

V

Dominant Output Voltage (CANL)

0.50

1.50

2.25

V

Dominant Differential Output

Voltage

1.5

2.0

3.0

V

Receiver

Min

Typical

Max

Units

Recessive Differential Input

Voltage (normal mode)

-1.0 - +0.5

V

Dominant Differential Input

Voltage (normal mode)

0.9 - Vcc

Parameter

Value

Units

Standby Current

10

μA

1.1 Pinout Table Diagram

Header J1

Pin

Signal

Description

1

N/C

Not Connected

2

CANL

CAN Low-Level Voltage I/O

3

GND

Power Supply Ground

4

N/C

Not Connected

5

N/C

Not Connected

6

GND

Power Supply Ground

7

CANH

CAN High-Level Voltage I/O

8

N/C

Not Connected

9

N/C

Not Connected

S1

GND

Power Supply Ground

S2

GND

Power Supply Ground

Header J2

Pin

Signal

Description

1

CS

Chip Select

2

MOSI

Master-Out-Slave-In

3

MISO

Master-In-Slave-Out

4

SCK

Serial Clock

5

GND

Power Supply Ground

6

VCC

Power Supply (3.3V/5V)

7

INT

Interrupt

8

RST

Reset

9

Rx0BF

Receive Buffer 0 Full Interrupt

10

Rx1BF

Receive Buffer 0 Full Interrupt

11

GND

Power Supply Ground

12

VCC

Power Supply (3.3V/5V)

Pmod CAN Reference Manual

Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.

Page 3 of 8

Header J3

Pin

Signal

Description

1

CANL

CAN Low-Level Voltage I/O

2

CANH

CAN High-Level Voltage I/O

3

GND

Power Supply Ground

Jumpers

Pin

Signal

Description

JP1

Loaded/ Unloaded

End of bus terminated with a combined 120Ω impedance/ Do not

terminate the end of the bus

JP2

Loaded/ Unloaded

Terminate the CAN bus lines with a capacitor to ground/ No termination

1.2 Physical Dimensions

The pins on the pin header are spaced 100 mil apart. The PCB is 1.8 inches long on the sides parallel to the pins on
the pin header and 1.4 inches long on the sides perpendicular to the pin header.

2 Functional Description

The Pmod CAN utilizes the Microchip MCP25625 to enable CAN communication with a variety of external devices.
A complete CAN solution with a controller and transceiver can be implemented on a system board by
communicating with the host board via the SPI protocol in SPI mode 0 or 3. The two differential lines on the
transceiver, CANH and CANL, enable balanced differential signaling to eliminate most of the electromagnetic field
(EMF) and provide high noise immunity within the system.

2.1 Serial Communication

The Pmod CAN communicates with the host board via the SPI protocol. By driving and keeping the Chip Select line
(pin 1) at a logic level low, users may communicate back and forth with the Pmod depending on whether or not
both sets of data lines are enabled. The embedded chip on the Pmod operates in SPI Mode 0 or 3, with data
captured on the rising edge of the clock and data transferred on the falling edge of the clock, and a minimum clock
cycle time of 100 nanoseconds as per Table 7-6 (page 70) of the Microchip MCP25625 datasheet.

Nine SPI instructions are available to read the status of the receiver, load a transmit buffer, modify bits in a register
and more. Most of the instruction commands are single byte instructions followed by an address byte. More
information is available in the Quick Start section as well as Section 5 (page 55) of the MCP25625 datasheet.

2.2 Register Details

2.2.1 CANINTE

The CANINTE register (page 51) enables the generation of interrupts on Pin 7.