Cypress CY8CKIT-026 User manual

CE211027 - CAN Communication Between
FM4-S6E2Gx Series and PSoC®4 M-Series
Using CY8CKIT-026 CAN and LIN Shield Kit
www.cypress.com Document No. 002-11027 Rev.*A 1
Objective
This code example demonstrates CAN communication between FM4-S6E2Gx Series & PSoC® 4 M-Series using the
CY8CKIT-026 CAN and LIN Shield Kit.
Overview
This code example demonstrates the configuration of FM4 S6E2GM Pioneer Kit and CY8CKIT-044 for CAN communication
using CY8CKIT-026 as the CAN transceiver. FM4 S6E2GM acts as the CAN transmitter (Tx) and PSoC®4 M as the CAN
receiver (Rx). The CAN transmitter sends data for ON/OFF status, color, and brightness of an RGB LED. This data is
transmitted over the CAN; at the CAN receiver, the RGB LED is configured to reflect the received data.
Requirements
Tool: PSoC Creator™3.3 SP1 (PSoC 4 M-Series) or later, Keil µVision®5 (FM4 S6E2Gx series).
Programming Language: C (Armcc V5.05, ARM GCC 4.9.3 and MDK compilers)
Associated Parts: 4200-M and 4100-M, FM4
Related Hardware: CY8CKIT-044 –PSoC 4 M-Series Pioneer Kit, FM4-176L-S6E2GM, two CY8CKIT-026 kits
Design
This code example consists of two projects; one for the CAN transmitter, and one for the CAN receiver. Figure 1. CAN
Network Topologyshows the hardware connections between the kits.
Figure 1. CAN Network Topology
FM4-S6E2GM
PIONEER KIT CY8CKIT-026 CY8CKIT-026
CAN-Tx
CAN-Rx CAN_H
CAN_L
CAN-Tx
CAN-Rx
C_Tx
C_Rx C_Rx
C_Tx
Jumper
Wires Jumper
Wires
DB9
connector
CN10_3
CN7_9
P0.0
P0.1
CY8CKIT-044
(CAN_Rx)
RGB LED
Computer
(HyperTerminal)
UART_Tx UART_Rx
3V3
GND
V3.3
GND GND GND
V3.3V3.3
The transmitter project continuously transmits LED ON/OFF status, color, and brightness values. The receiver project controls
its LEDs accordingly.

CAN Communication Between FM4-S6E2Gx Series and PSoC®4 M-Series Using CY8CKIT-026 CAN and LIN Shield Kit
www.cypress.com Document No. 002-11027 Rev.*A 2
CAN_Tx_FM4 Project
This project is configured to work as a CAN transmitter. The project continuously sends three bytes of data when it is powered,
as shown in Figure 2. Data Sent by CAN Tx, to the CAN receiver to the control ON/OFF status, color, and brightness of the
LED. The brightness data is incremented and updated in the data frame. Once the brightness reaches the maximum value, the
LED is turned off and the color of the LED is changed.
Figure 2. Data Sent by CAN Tx
1st BYTE
ON-OFF Status 3rd BYTE Brightness
2nd BYTE
Color
The project changes LED color and brightness as shown in Figure 3.
Figure 3. Waveform Representing RGB Pattern
Brightness
MAX
MIN
ON/OFF=ON
Brightness=MIN
LED=RED LED=GREEN LED=BLUE LED=RED
Brightness = MAX
(ON/OFF=OFF, set
Brightness=MIN)
Again set
ON/OFF=ON
Time

CAN Communication Between FM4-S6E2Gx Series and PSoC®4 M-Series Using CY8CKIT-026 CAN and LIN Shield Kit
www.cypress.com Document No. 002-11027 Rev.*A 3
CAN_Rx_PSoC4M Project
This project receives the CAN data sent from the CAN_Tx_FM4 project. The received data is a packet of three bytes
consisting of the ON/OFF status, color, and brightness, as Figure 4 shows. The color and brightness of the RGB LED on the
receiving CY8CKIT-044 is controlled based on the received data.
Figure 4 Controlling LED According to Received Data Frame.
ON REDON brightnessREDON brightnessREDON brightnessRED
ON brightnessGREEN
ON REDON brightnessREDON brightnessREDON brightnessBLUE
CY8CKIT-
026
CY8CKIT-
026
CY8CKIT-
026
CY8CKIT-044
CY8CKIT-044
CY8CKIT-044
LED
LED
LED
FRAME SHIELD
Case1
Case2
Case3
Design Considerations
CAN_Tx_FM4 Project
FM4 S6E2GM controller supports two channels of CAN. This project uses CAN channel 0. The corresponding Rx and Tx pins
are assigned to P16 and P17 respectively. These pins are on CN10_3 and CN7_9 respectively on the FM4 kit.
CAN_Rx_PSoC4M Project
CAN is a fixed-function Component. Dedicated pins must be used. In this project, P0.0 is used for CAN_Rx and P0.1 is used
for CAN_Tx.
The UART Component displays the received CAN messages on a serial terminal. UART is used as Tx only, and the UART Tx
pin is assigned to P7.1.

CAN Communication Between FM4-S6E2Gx Series and PSoC®4 M-Series Using CY8CKIT-026 CAN and LIN Shield Kit
www.cypress.com Document No. 002-11027 Rev.*A 4
Hardware Setup
CAN Tx Hardware Connections
To use CY8CKIT-026 with an FM4 Kit (FM4 S6E2GM Pioneer Kit), make the following connections:
To connect CY8CKIT-026 with the FM4 kit, connect extra headers to CY8CKIT-026 as shown in Figure 5.
Figure 5. FM4 Kit with Extra Headers

CAN Communication Between FM4-S6E2Gx Series and PSoC®4 M-Series Using CY8CKIT-026 CAN and LIN Shield Kit
www.cypress.com Document No. 002-11027 Rev.*A 5
Connect CY8CKIT-026 on top of the FM4 kit as shown in Figure 6. CY8CKIT-026 Connected to FM4 Kit
Make connections for CAN Tx and Rx on CY8CKIT-026 per Table 1.Connections on CY8CKIT and Figure 7
Figure 6. CY8CKIT-026 Connected to FM4 Kit
Table 1.Connections on CY8CKIT-026
J2_7 (A3)
J19_2(CAN1_Rx)
J3_9(SDA)
J19_1(CAN1_Tx)
Connect a micro USB cable to the FM4 kit as shown in Figure 7.
Place the jumper J13 on CY8CKIT-026.

CAN Communication Between FM4-S6E2Gx Series and PSoC®4 M-Series Using CY8CKIT-026 CAN and LIN Shield Kit
www.cypress.com Document No. 002-11027 Rev.*A 6
Power the Shield kit with a 12-V/1-A input and connect the DB9 connector to CY8CKIT-026 as shown in Figure 7.
Figure 7. CY8KIT-026 and FM4 Kit

CAN Communication Between FM4-S6E2Gx Series and PSoC®4 M-Series Using CY8CKIT-026 CAN and LIN Shield Kit
www.cypress.com Document No. 002-11027 Rev.*A 7
CAN Rx Hardware Connections
To use CY8CKIT-026 with CY8CKIT-044, make the following connections:
Make sure that the jumper J9 on the baseboard (CY8CKIT-044) is in the 3.3V position.
Connect CY8CKIT-026 on top of CY8CKIT-044 as shown in Figure 8.
Figure 8. Connection of CY8CKIT-044 with CY8CKIT-026
Place the jumper on pin 2 and 3 of the J20 connector.
Connect J2_13 to J19_2 (CAN1_RX) and J2_15 to J19_1 (CAN1_TX) using connecting wires as shown in Figure 7.
Figure 9. CAN TX and RX Pin Connections
Connect a USB cable to CY8CKIT-044 for observing the LED data on Terminal.

CAN Communication Between FM4-S6E2Gx Series and PSoC®4 M-Series Using CY8CKIT-026 CAN and LIN Shield Kit
www.cypress.com Document No. 002-11027 Rev.*A 8
Connect a DB9 connector to CY8CKIT-026 as in Figure 10.
Figure 10.DB9 Connector
Components
Table 2. Peripherals Used –CAN_Tx_FM4lists the peripherals used in the CAN_Tx_FM4 project, as well as the hardware
resources used by each.
Table 2. Peripherals Used –CAN_Tx_FM4
Peripherals
Hardware Resources
CAN
1 CAN channel
I/Os
2 CAN Rx and Tx
Table 3 lists the PSoC Creator Components used in the CAN_Rx_PSoC4M project, as well as the hardware resources used
by each.
Table 3. PSoC Creator Components –CAN_Rx_PSoC4M
Component
Hardware Resources
CAN
1 CAN block
PWMs
3 TCPWMs
UART
1 SCB UART
Pins
2 CANs: Rx and Tx
3 LEDs
2 UARTs: Rx and Tx
Clock
1 Clock Component

CAN Communication Between FM4-S6E2Gx Series and PSoC®4 M-Series Using CY8CKIT-026 CAN and LIN Shield Kit
www.cypress.com Document No. 002-11027 Rev.*A 9
Parameter Settings
CAN_Tx_FM4 project
The CAN peripheral block is configured using the associated peripheral registers. See the 32-BIT MICROCONTROLLER FM4
Family Communication Macro Part PERIPHERAL MANUAL for more information on the CAN peripherals. This project uses CAN
peripheral and I/O pins. In this project, CAN channel 0 is used for communication. P16 and P17 pins are configured as Rx and
Tx respectively.
The following are the steps for configuring CAN and pins:
Select P16 and P17 using the PFR3 register.
Configure the selected pins to CAN Rx0_0 and Tx0_0 by using the EPFR09 register. Set bits 26 and 24 of this register to
configure the I/O pins as CAN pins.
Set the clock gating for CAN channel 0 using the CKEN2 register.
To configure CAN channel 0, first set CAN in initialization mode using the control register CTRLR, and allow access to the
Bit Timing Register (BTR) using CTCLR.
Set the CAN prescalar using the CANPRE register. Writing 0x02u sets CAN Prescaler to 1/4 and this CAN System Clock
to 40 MHz based on PLL=160 MHz.
Write 0x4993u to the Bit Timing Register (BTR) .This sets the baud rate to 125 kbps with the following CAN controller
parameters for bit timing:
Tseg1=10
Tseg2=3
SJW=3
BRP=16
Use the CTCLR register to change CAN to run mode and disable the access to the BTR register.
CAN_Rx_PSoC4M Project
The following are the steps for configuring the CAN Component in PSoC Creator for PSoC 4M:
Configure the clocks to use Trim with WCO option.
The CAN Component needs a clock with an accuracy of ±1.58 percent or better. However, the internal main oscillator (IMO) in
PSoC 4 M is 2 percent accurate; therefore, you must either trim the IMO or use an external clock. These settings must be
done before the CAN Component is configured because the timing section in the Component configuration will be updated
based on this clock. If the clock is not selected before the Component is configured, the Component displays a warning to do
so, as Figure 11 shows.

CAN Communication Between FM4-S6E2Gx Series and PSoC®4 M-Series Using CY8CKIT-026 CAN and LIN Shield Kit
www.cypress.com Document No. 002-11027 Rev.*A 10
Figure 11. CAN Component Clock Accuracy Warning
In the clock configuration wizard of the CAN_Rx_PSoC4M.cydwr file, the IMO can be trimmed to an accuracy of 0.5 percent
using the watch crystal oscillator (WCO) in PSoC 4 M. To trim the IMO, first select LFCLK as the WCO and select Trim with
WCO in the IMO section, as
Figure 12 shows.
Figure 12. Clock Configuration
Configure the CAN Component
Drag and drop a CAN Component from the Component Catalog to TopDesign. Double-click the Component to configure it.
The settings in the General tab are left with the default selections.
In the Timing tab, select the Desired baud rate. The table with different timing parameters will be updated based on the
selected baud rate. Then, select one of the rows with the criteria that Variance is minimal and Sample point is around 80
percent, as shown in Figure 13.Double-click on that row to make sure that the values are updated in the settings section.