MYC-C437X CPU Module for Hardware Design Reference

About MYC-C437X CPU Module
Measuring only 45mm by 60mm, the MYC-C437X CPU Module designed by MYIR is a System-on-Module (SoM) which was built around TI Sitara AM437x ARM Cortex-A9 processor and integrates 512MB DDR3 (supports up to 2GB), 4GB eMMC Flash (can be replaced by Nand Flash), 32KB EEPROM, Gigabit Ethernet PHY and PMIC on board. It has two 0.8mm pitch 2*50-pin board-to-board connectors to provide an interface for the base board to carry all the I/O signals to and from the CPU module. The module is able to run Linux and TI SYS/BIOS v6.45 operating systems. It is ideal for industrial embedded applications and supports extended working temperature ranges from -40 to 85 Celsius. 1GHz TI Sitara AM437x ARM Cortex-A9 32-Bit RISC processor
 * 512MB DDR3 SDRAM
 * 4GB eMMC (can be replaced by Nand Flash)
 * 16MB QSPI FLASH (DNP)
 * 32KB EEPROM
 * Gigabit Ethernet PHY
 * PMIC TPS65218
 * Two 0.8mm pitch 2*50-pin board-to-board connectors

About TI AM437x
The TI AM437x high-performance processors are based on the ARM Cortex-A9 core. The processors are enhanced with 3D graphics acceleration for rich graphical user interfaces, as well as a coprocessor for deterministic, real-time processing including industrial communication protocols, such as EtherCAT, PROFIBUS, EnDat, and others. Customers using this next generation solution will see an increase in performance, as well as extensive reuse from the ARM Cortex-A8 offerings.

Increasing performance and peripheral support
Sitara AM437x processors deliver the right balance of

Performance

 * Up to 1GHz Sitara™ ARM® Cortex®-A9 32-Bit RISC processor
 * 3D graphics accelerator
 * On-chip quad-core PRU co-processor for real-time processing
 * Improved vector floating-point unit

Interfaces

 * LPDDR2/DDR3
 * QSPI
 * Display subsystem

Connectivity

 * Two parallel camera ports
 * Dual-port 1Gb Ethernet switch
 * Two independent, eight-channel ADCs
 * WiLink connectivity drivers
 * Industrial protocols via PRU-ICSS

AM437x Device Comparison
There are four different processor types of the AM437x processor family (AM4376, AM4377, AM4378 and AM4379), they are pin-to-pin and software compatible. Below Figure 1-2 shows the main differences among the four AM437x compatible devices.

Hardware Design Reference
Here we will introduce how to use the MYC-C437X CPU Module for your hardware design reference. Below are the main contents:
 * MYC-C437X Expansion Interfaces
 * Power Supply
 * TF (MMC)
 * LCD
 * Camera
 * Industrial Ethernet
 * Industrial Real-time Serial Port
 * USB
 * UART/RS485/CAN interface
 * EnDAT/eQEP/eCAP/eHRPWM

MYC-C437X Expansion Interfaces
The AM437x ZDN package has 491 pins, there are 163 GPIOs available besides some dedicated pins such as EMIF (for SDRAM connection), USB and ADC. These GPIOs all can be reused to support numerous interfaces.

Except the signals of power supply and 4 Ethernet differential pairs, all other signals are brought out directly from the pins of AM437x processor including LCD, Camera, MMC, RGMII/GMII, USB, UART, I2C, SPI, McASP, McSPI, QSPI, HDQ, ADC, JTAG as well as PRU-ICSS which contains the eCAP, eHRPWM, EnDAT, MII and UART signals.

Power
Isolated power supply will always be used in industrial field in order to improve the Electromagnetic Compatibility (EMC). Here we will give an introduction for the power input requirements of MYC-C437X CPU Module. It only needs 5V and 3.3V two input voltage for the MYC-C437X CPU Module power supply. The 5V input power will supply power to the CPU, Memory, EMMC, and Ethernet PHY after transferred by PMIC TPS65218. The 3.3V input voltage is used for RTC but it is not a must. Furthermore, the MYC-C437X CPU Module can provide 3.3V and 1.8V two output voltage. The output current of 3.3V voltage is up to 1.6A. If 3.3V@1.6A output is needed, you should assure 5V@2A input. As shown in below Figure 1-5, the +5V and VBAT (3.0V) are the power supply input terminals, the V3_3D and V1_8D are the power supply output terminals.

TF Card Interface
The TF card has two main functions in embedded system applications. One is for storing system booting files and image files on systems debugging stage and the other is to be used as mass storage device. The MYC-C437X provides MMC0 interface which can support up to 24MB/s in High-speed SD mode 4-bit data transfer. Users can reuse these GPIOs for other functions if they don’t need the MMC0 in their design.

LCD Interface
The AM437x LCD signals are multiplexed with PR1_MII0 (AM437x supports 2 PRU MII) and Camera. Its signals have up to 8 types of multiplexed modes. The multiplexer is needed when using the same pins to implement different interfaces. The performance parameters of the multiplexer such as switch speed and impedance are key factors needed to be considered.

Camera Interface
The MYC-C437X CPU Module supports two camera inputs (VPFE), which is used for connection to CCD cameras or BT.656 compliant video encoders. The pins of camera have also reused with others, they can be used as the GPIO, MMC, QSPI, SPI, eHRPWM, interruption and other sources if you don’t need camera.

Industrial Ethernet
The AM437x PRU cores can support two MII Ethernet interfaces which are used for supporting Ethernet/IP, PROFINET RT/IRT (AM4377 and AM4379 can additionally support EtherCAT and POWERLINK protocols). The MYC-C437X CPU Module has two industrial Ethernet MII interfaces, one of them is multiplexed with LCD signals.

PROFIBUS
Profibus has 3 standards FMS, DP and PA which are used in different applications. Profibus DP is the most commonly used. It can be easily installed with diverse topology, easily implemented with reliable real-time communication, comprehensive functions and excellent performance which make Profibus DP applies to all kinds of industrial automation applications. It uses the standard RS485 for data communications and its transmission rate is up to 12Mbps and the transmission distance can reach 23.8km. It is transmitted through twisted pair cables or optical cables. The advantage of this protocol is the short response time and strong anti-interference capabilities. It’s easy to be extended and can connect up to 125 nodes.

The AM437x PRU cores can support two PUR UART interfaces. The communication speed is up to 3Mbps. The MYC-C437X CPU Module provides two RRU UART interfaces. In order to improve the system anti-interference ability, the Profibus interface circuit usually uses optical coupler to implement the isolated data signal transmission.

USB
The AM437x processor is able to provide 2 independent USB 2.0 interfaces which can support USB host or USB device but it cannot support OTG. The MYC-C437X CPU Module expansion interface has extended 2 USB.

UART/RS232/RS485/CAN
The MYC-C437X CPU Module supports 6 UARTs and 2 CAN. One of the UARTs is used for Debugging. In order to ensure the reliable and stable signal transmission, the high-speed optical coupler or magnetic coupling are usually needed to use for implementing the isolated data signal transmission.

EnDat/eQEP/eCAP/eHRPWM
eQEP (Enhanced Quadrature Encoder Pulse) belongs to the peripheral of AM437x but not in PRU part. It is usually used to detect the location and rotate speed of motor. The driver circuit of EnDat2.2 is using standard RS485. eCAP (Enhanced Capture) is for signal acquisition. eHRPWM (Enhanced High-Resolution PWM) generates PWM signals. The MYC-C437X CPU Module takes full features of the AM437x processor and supports up to 3 eQEP, 3 eCAP and 6 eHRPWM.

Useful Link

 * Official website
 * TI AM437x Datasheet
 * TI AM437x Technical Reference Manual