SOM37X Hardware Design Guide
Content
1 Introduction ....................................................................................................................... 3
2 Change History .................................................................................................................. 3
2.1 Change History ........................................................................................................... 3
3 SOM37x Overview ............................................................................................................. 3
3.1 more information about SOM37x .............................................................................. 3
4 Power supply ..................................................................................................................... 4
4.1 Power net descriptions .............................................................................................. 4
4.2 Power on sequence .................................................................................................... 4
5 Module Configuration and Initialization ........................................................................... 5
5.1 Module Reset ............................................................................................................. 5
5.2 Module Configuration and control pins ..................................................................... 5
5.3 Boot Modes ................................................................................................................ 6
6 Peripherals ......................................................................................................................... 7
6.1 DSS and McSPI ............................................................................................................ 7
6.2 GPMC .......................................................................................................................... 7
6.3 HSUSB ......................................................................................................................... 8
6.4 I2C ............................................................................................................................... 9
6.5 MMC ........................................................................................................................... 9
6.6 UART ......................................................................................................................... 10
6.7 JTAG .......................................................................................................................... 10
7 4 x50 pin expansive connector of SOM37x ..................................................................... 10
Table Content
Table 1 : Change History ........................................................................................................... 3
Table 2 : Power net descriptions .............................................................................................. 4
Table 3 : Control nets ................................................................................................................ 6
Table 4 : normal boot sequence from multiple source ........................................................... 6
Figure Content
Figure 1 : Power on sequence .................................................................................................. 5
Figure 2 : Reset circuit connections ......................................................................................... 5
Figure 3 : boot configuration circuit ......................................................................................... 6
Figure 4 : DSS bus circuit .......................................................................................................... 7
Figure 5 : GPMC bus application circuit ................................................................................... 8
Figure 6 : OTG application circuit ............................................................................................. 8
Figure 7 : HSUSB bus application circuit .................................................................................. 8
Figure 8 : I2C and FRAM ........................................................................................................... 9
Figure 9 : MMC bus application circuit .................................................................................... 9
Figure 10 : UART application circuit ....................................................................................... 10
Figure 11 : JTAG connector ..................................................................................................... 10
Figure 12 : 4 x50 pin expanded connector of SOM37x-A1 .................................................... 11
Figure 12 : 4 x50 pin expanded connector of SOM37x-B2 .................................................... 11
1 Introduction
This document is the Hardware design guide for the SOM37x. This document provides detailed
information on the overall design and usage of the SOM37x from the system level perspective. It
is not intended to provide detailed documentation of the processor or any other component used
on the board. It is expected that the user will refer to the appropriate documents for these
devices to access detailed information.
2 Change History
2.1 Change History
Table 1 tracks for the changes made for each revision of this document.
Table 1 : Change History
Revision Changes Date By
A1 Initial release 2011-03-30 Chalay
A2 Update USB
application schematic
2011-9-23 Chalay
A3 Add 2011-12-16 Chalay
3 SOM37x Overview
The SOM37x module based on TI’s AM/DM37x processor family is a embedded SOM (system on
module) designed by EMA-Tech. SOM37x support Linux-2.6.31、WinCE6.0、Android and other
embedded operating system. SOM37x provides a mass of software resources such as DVSDK,
OpenGL ES2.0, OGRE and etc.
The SOM37x module use TPS65951 as PMIC and Package-on-a-Package (PoP) Combination
Memory which includes NAND Flash and LP-DRAM as memory storage. The NAND Flash and
LP_DRAM are compatible with other Combination memory from Micron, the density of NAND
Flash is up to 1GB, and the LP_DRAM up to 256MB.
3.1 more information about SOM37x
For information about SOM37x, please see the document SOM37X User Manual provided by
EMA-TECH, the SOM37X User Manual describes electrical specifications, connector specifications
and etc.
You can get the SOM37X User Manual from EMA-TECH, please contact EMA’s Technical Support.
If you need more information about AM/DM37x and TPS65951, please refer to www.Ti.com for
more information.
4 Power supply
4.1 Power net descriptions
The SOM37x has several power net, please refer to Table 3 for details. All the signal in the table 2
are all connected to TPS65951.
Table 2 : Power net descriptions
NET Voltage Direction
VDD_SOM 3.3V I
VDD_IO 1.8V O
VDD_MMC1 3V/1.8V O
VBUS_HSUSB0 5V O
VDD_RTC 3V I
VDD_AUX2 1.8V O
VDD_SOM : The main power source to SOM37x, it is connected to the PMIC TPS65951.
VDD_IO : This signal is the reference voltage of IO net , it is just designed to provide a reference
voltage for level shifter and can’t be used as 1.8V power supply.
VDD_MMC1 : The power supply for MMC1 card, it provide 1.8V/3.3V power supply just when the
SOM37x is configured to boot from MMC1 card.
VBUS_HSUSB0 : The power supply for HSUSB0(OTG), it provide 5V(100mA max) power supply
just when the SOM37x is configured to boot from HSUSB0.
VDD_RTC : The backup battery supply.
VDD_AUX2 : VAUX2 LDO output voltage supply.
4.2 Power on sequence
Figure 1 shows the power on sequence of SOM37x.
VDD_SOM
T2.PWR_ON
T2.REGEN
VDD_IO
SYS_nRESWARM
T2.SYSEN
SYS_nRESPWRON
1068 μs - 3 MHz oscillator setting + clock switch
Pulled up by VDD_IO power net with 10K resister
29.114 ms – Output signal enable the
processor
Pulled up by VDD_SOM power net with 10K
resister
4608 μs battery detection
4536μs - System Enable
Figure 1 : Power on sequence
T2.PWR_ON is pulled up with 10K resister internal and SOM37x boots automatically when
VDD_SOM power supply is detected. T2.PWR_ON should be NC when this control signal is not
used in design.
SYS_nRESPWRON is the reset signal of AM/DM3730, Using this pin carefully is recommended.
5 Module Configuration and Initialization
5.1 Module Reset
There are one way to reset the SOM37x and these are described in the SOM37X User Manual.
The 2 external resets, SYS_nRESPWRON and SYS_nRESWARM.
SYS_nRESPWRON is the reset open-drain input/output signal and pull up with 4.7K resister.
SYS_nRESPWRON is connected to AM/DM3730 input pin directly, and controlled by the output
signal nRESPWRON of TPS65951 indirectly. In the hardware design, the designer can use this
reset signal to reset the SOM37x and reset the component on the baseboard at power on
sequence of SOM37x.
SYS_nRESWARM is the warn reset come out from AM/DM3730, this signal should be used to
reset output signal.
Refer to TI’s AM/DM37x TRM for further information on using this two signals.
Figure 2 shows the reset circuit connections
Figure 2 : Reset circuit connections
5.2 Module Configuration and control pins
Refer to AM/DM37x TRM for more configuration and control pin information.
Device
nRESET
SOM37x
SYS_nRESPWRON
SYS_nRESWARM
Reset button
Table 3 : Control nets
NET Voltage Direction
SYS_nRESPWRON 1.8V I/O
SYS_nRESWARM 1.8V I/O
T2.PWR_ON 3.3V I
T2.REGEN 1.8V O
T2.SYSEN 1.8V O
T2.USBCHRG_ENZ 1.5V(VPRECH) O
T2.USBCHRG_STATZ 1.5V(VPRECH) I
T2.CHRG_DET_N 1.5V(VPRECH) O
T2.MANU_BRIX 1.8V O
SYS_BOOT[5:0] 1.8V I
5.3 Boot Modes
The AM/DM37x provides the option of booting from multiple sources. The boot mode is
controlled by the SYS_BOOT pins of the processor. Six external pins (sys_boot[5:0]) are used to
select interfaces or devices for booting.
Table 4 shows the normal boot sequence from multiple source. Refer to AM/DM37x TRM for
more boot configuration information.
Table 4 : normal boot sequence from multiple source
OMAP35x Processor Pins Boot Method
Default SYS_BOOT[5:0]= 101111 USB, UART3,MMC1,NAND
Alternate SYS_BOOT[5:0]= 001111 NAND, USB, UART3,MMC1
Alternate SYS_BOOT[5:0]= 001110 XIPwait, DOC,USB, UART3,MMC1
Alternate SYS_BOOT[5:0]= 000110 MMC1 USB
Figure 4 shows the boot configuration circuit designed by EMA.
Figure 3 : boot configuration circuit
6 Peripherals
The AM/DM37x multiple media processor a mass of peripheral and the SOM37x lead out of all
signal. Each peripheral section includes recommendations on how to handle pins on interfaces.
Refer to AM/DM37x TRM or contact us to to get more information about how to use the
SOM37x.
6.1 DSS and McSPI
Figure 5 shows the DSS and McSPI bus application circuit, in this circuit, two ic level shifter and a
AD converter are used for DSS, the McSPI bus is connected to touch screen controller.
Figure 4 : DSS bus circuit
6.2 GPMC
Figure 5 shows the application circuit of GPMC bus, this circuit connect the Ethernet IC and the
SOM37x through GPMC bus.
Figure 5 : GPMC bus application circuit
6.3 HSUSB
Figure 6 shows the OTG bus application circuit.
Figure 6 : OTG application circuit
Figure 7 shows the HSUSB bus application circuit.
Figure 7 : HSUSB bus application circuit
This circuit is the USB part of the board SBC3530_B2 of EMA, it fix two issues of the board
SBC3530_B1.
ISSUE 1. USB failure on CON9. This issue relates to the intermittent failure of both USB ports
on CON9. It appears on all tested boards. This problem occurs only on system boot up and does
not occur during system operation i.e. if the system is already running this error does not occur.
ISSUE 2. USB failure on CON8 and CON9. This issue is apparent on a number of boards. During
system operation, USB functionality will fail on CON8 and CON9 and an error message is
displayed over the serial connection (see attached system log file). This error will usually occur
after approximately 1 minute of operation on the board. It has been observed that plugging a
USB storage device into CON8 or CON9 can possibly induce the failure, but this has not been
confirmed. After a time period the USB functionality is available. The time period varies from 5
mins to 20 mins upwards. During this time the system is slow in operation.
About more details charged between SBC3530_B1 and SBC3530_B2, please refer to these two
schematics.
6.4 I2C
Figure 8 : I2C and FRAM
6.5 MMC
Figure 9 : MMC bus application circuit
6.6 UART
Figure 10 : UART application circuit
6.7 JTAG
Figure 11 : JTAG connector
7 4 x50 pin expansive connector of SOM37x
SOM37x use 4 board-to-board connector as the expansive connector, 50 pin connector are all
used. See figure 13 for the signal assignment of each pin or see the document SOM37X User
Manual for more details of signal descriptions.
Figure 12 : 4 x50 pin expanded connector of SOM37x-A1
Figure 13 : 4 x50 pin expanded connector of SOM37x-B2
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