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Temporary CPLD Description

This chapter is part if an older description and can be use until the newer one is finished

Overview: System Management Controller (SC)

A Lattice XO2-1200 CPLD is used as a System Management Controller (referred to as SC in the manual). The SC is responsible for power sequencing, reset generation and Zynq initial configuration (mode pin strapping). Moreover, some on-board ICs are connected to the SC that provides level shifting.

It is possible for the default SC functions and pin functions to be changed. This can be done as a request to Trenz Electronic or it is possible for the user to generate their own designs. Please contact us for details.

The SC wakes up when the 3.3V input power rises above 2.1V (VIN voltage is not needed). The SC can turn on or off all of the other supplies on the module (except in no power sequencing mode when the 1.0V and 1.8 V supplies are forced to start immediately when power is applied to the module).

Custom SC Programming

SC customization is available either by requesting new features or with special agreement by using the users own code. SC code can be updated in the system using the I2C interface. Please contact us for details.

SC B2B Pins

SC is connected directly to the following B2B Pins.

NameModeDefault functionAlternativeDescription
EN1input, weak pull-upPower EnableIOHigh enables the DC-DC converters and on-board supplies. Not used if NOSEQ=1
PGOODoutput, open drainPower goodSCL or IOForced low until all on-board power supplies are working properly.
Attention: During CPLD programming, this pins is high impedance
MODEinput, weak pull-upBoot modeSDA or IOForce low for boot from the SD Card. Latched at power on only, not on soft reset!
RESINinput, weak pull-upReset inputIOActive Low Reset input, default mapping forces POR_B reset to Zynq PS
NOSEQinput, weak pull-downPower sequencing ControlOutputForces the 1.0V and 1.8V DC-DC converters always ON when high. Can be used as an I/O after boot.
JTAGSELinputJTAG Chain selectnone, fixedkeep GND or pulled low for FPGA JTAG access.


This is a dedicated input that forces the module's 1.0V and 1.8V supplies to be enabled if high. This pin has a weak pull-down on the module. If left open the module will power up in normal power sequencing enabled mode. This pin is 3.3V tolerant. This pin is also connected to the System Management Controller. The SC can read the status of this pin (that is it can detect if the module is in power sequencing enabled mode). The SC can also use this pin as output after normal power on sequence. Please check the SC description for the function. SC rev 0.02 maps Ethernet PHY LED0 to NOSEQ by default (the mapping can be changed by software after boot).

No Sequencing mode

If the module is powered from a single 3.3V supply and power sequencing is disabled, then NOSEQ pin should be powered from the main 3.3V input. That is VIN, 3.3Vin and NOSEQ should all be tied together to the input 3.3V power rail. Sequencing mode should not be used if VIN is not 3.3V.

Normal mode

For normal operation leave NOSEQ open or pull down with a resistor.

Normal mode with user function on NOSEQ

NOSEQ can be used as an output after boot. NOSEQ must be low when 3.3V power is applied to the module. Common usage is an LED connected between NOSEQ and GND.

SC pins to the FPGA

Schematic net nameDefault functionDirectionSC pinFPGA pinDescription
X1I2C Clock from FPGAfrom FPGAF1L16SCL from EMIO I2Cx
X7I2C Data from FPGAfrom FPGAM1N22SDA from EMIO I2Cx
X5I2C Data to FPGAto FPGAJ1P22SDA to EMIO I2Cx

--not used on TE0720-02

K16normally not used tied to fixed level by SC

It is recommended to use Vivado IP Core available for 2014.2 and later versions.

Default Mode

At power up the System Management Controller starts with default settings.

Pin/FunctionUsed as/Mapped to Notes
ETH PHY CONFIGTied logic lowPHY Address set to 0
ETH CLK125MHzPass through FPGA B34 SRCC pin
ETH Clock EnableTied logic high
ETH PHY ResetInternal RESET
RTC Interrupt
MEMS Interrupt 1 
MEMS Interrupt 2-
eMMC ResetInternal RESET
USB PHY ResetInternal RESET
FPGA PUDCTied logic low 
FPGA PROG_BTied logic high
Zynq Cascaded JTAG Enabled (pulled low) 
Zynq boot mode SPI or SD, depending on bootmode pin 
Zynq SRSTTied logic high 
Zynq PORInternal POR/Reset
PLLNot used
LED2System Status LED
NOSEQ InputNOSEQ at power, LED out after boot
Power Good 1.5V

Power Good VTT

MODE Input

I2C AddressFunction
0x20Status reg 1
0x21Status reg 2

LED Control Status

The TE0720 on-board LED devices can be remapped to different functions.

Input port bitMapped to
0Ethernet PHY LED0 output
1Ethernet PHY LED1 output
2Ethernet PHY LED2 output
4Returns RESIN pin level
5Returns EN1 pin level
6Returns NOSEQ pin level
7Returns MODE pin level

LED1 and LED2 function can be changed from the default behaviour using output port bits (3..0)

 D3D2D1D0 LED1 function as
 0000Default (MIO7)
 0001ETH PHY LED0 
 0010ETH PHY LED1 

SC Demystified

System Controller (SC for short) was designed to allow ZYNQ PS system to access module special functions as early as possible without reducing the number of MIO pins that are fully user configurable.

This early communication channel is done using MIO52 and MIO53 pins that are used also as Ethernet PHY management interface for the on-board Gigabit PHY.

In order to simplify the boot process and reduce the number of time the PS peripherals need to be configured or re-initialized SC uses the same protocol on MIO52/MIO53 as the Gigabit PHY itself. This means that FSBL Configures all peripherals to their final function, allocating MIO52 as MIO52 as Ethernet MDIO Interface.

SC Controller appears as "Virtual Ethernet PHY" on the MDIO bus of PS Ethernet 0 Interface. This interface is already available when Zynq PL Fabric is not configured.

It would have been possible to use I2C Protocol on MIO52/MIO53 but in such case some multiplexing would be be needed to choose between two protocols, also it would be needed to change the Peripheral mapping after first init by the FSBL.

For use cases where Ethernet PHY on TE0720 is not used at all, it is still possible to configure SC with design that implements I2C Protocol on MIO52/MIO53 pins.

For most use cases the only need to use this interface is access to MAC Address info, this is normally done by u-boot loader that fetches the MAC Address bytes and sets its environment variables accordingly. Linux image will then also be started so that the MAC Address from EEPROM is used for Ethernet 0 Physical interface.

SC Firmware ver 0.02

This is the initial version of the System Controller with only a very limited function set implemented.

System Controller can be accessed as PHY with address 0x1A on the ETH0 Management bus (MIO pins 52, 53). Communication can be established anytime when ETH0 and management interface are enabled also before FPGA PL Fabric is configured.Version check

System Controller Firmware version and some other version info can be read with u-boot command mii info:

zynq-uboot> mii info
PHY 0x00: OUI = 0x5043, Model = 0x1D, Rev = 0x01, 100baseT, FDX
PHY 0x1A: OUI = 0x7201, Model = 0x01, Rev = 0x00,  10baseT, HDX

PHY at address 0x00 is the ETH0 onboard ethernet PHY Marvell 88E1512.

PHY at address 0x1A is the System Controller. OUI 0x7201 should be decoded as Model TE0720-01. Model 0x01 is Assembly option. Rev 0x00 is the firmware major revision for the System Controller (Rev 0 is the initial version).

Bit Decoding

Reg AddrBitsu-boot ENV VariableDescription
215:0boardupper bits of SoM Model
315:10boardlower bits of SoM Model
415:14boardFPGA Speed Grade (1, 2 or 3)
413:12boardFPGA Temperature Range (0=Commercial, 1=Extended, 2=Industrial, 3=Automotive)
411:8-Assembly Variant
47:0scverSC Firmware Revision Minor number

Customized u-boot reads and decodes the model and assembly variant information and stores in readable format in environment variables.

zynq-uboot> printenv board

Reading MAC Address

With u-boot command mii read:

zynq-uboot> mii read 1a 9-b
addr=1a reg=09 data=0004
addr=1a reg=0a data=A3AC
addr=1a reg=0b data=3911

This command will read MAC Address from the System Controller. Note: This only works if the ETH0 interface is enabled and if FSBL has enabled MII Management console on ETH0 Interface. 0004A3 is OUI part, AC3911 is the serialized part (lower bits of MAC address).

Customized u-boot does read MAC Address and stores it in environment variables as required, as a result, proper MAC address is used both in u-boot as also in Linux. Setting up MAC Address for Linux involves dynamic rewrite of FDT, this is done with u-boot script that starts Linux.

SC Registers

Most registers and functions are available via ETH PHY Management interface (MIO pins 52 and 53).

AddrR/WRegister nameDescripion


2ROID1Identifier Register 1
3ROID2Identifier Register 2
4ROID3Identifier Register 3
5RWCR1Control Register 1: LED's
6RWCR2Control Register 2; XIO Control
7RWCR3Control Register 3; Reset, Interrupt
8ROSR1Status Register
9ROMAChiHighest bytes of primary MAC Address
0xAROMACmiMiddle bytes of primary MAC Address
0xBROMACloLowest bytes of primary MAC Address
reserved do not use
0xDRWMMD_CRMMD Control Register
0xERWMMD_ADMMD Address/Data
reserved do no use
reserved do not use

Register CR1

11:8Noseq MUX
DefaultMIO7Mode BlinkPHY_LED0
REV 05, UART activity
REV 05

REV 05

Register CR2

15:12XCLK select
11:8XIO6 select
7:4XIO5 select
3:0XIO4 select

Signal XIO4

XIO4 selectSignal out value
"0110"'Z' (Configured as input)
all othersPHY_LED0

Signal XIO5

XIO5 selectSignal out value
"0110"'Z' (Configured as input)
all othersPHY_LED1

Signal XIO6

XIO6 selectSignal out value
"0110"'Z' (Configured as input)
all othersPHY_LED2

Signal XCLK

XCLK SelectSignal out value
"0010"Internal Oscillator Out ~24.18 MHz
all others125 MHz

Signal SHA_IO

XIO4 selectSignal out value
all others'Z' (Configured as input)

Signal MAC_IO

XIO4 SelectSignal out value
all othersConnected to internal MAC read block

System Controller version 0.02 does not support extended address space - registers 0xD and 0xE are read-write accessible but do not have any function. In feature revision extended address will be used to control SC PLL and other features.

0enable INT1
1enable INT2
2enable RTC_INT
3enable PHY_LED2
7EN_ETH_CLK (not CR3, default enabled)

CR3 bit description

Interrupt can be selected instead of PHY_LED2 on XIO6 pin, by setting CR2 bits 11 downto 8 to "0111"

Overview: On-board LEDs

There are 3 on-board LEDs, with two of them connected to the System Management Controller and one to the Zynq PL (Done pin).

NameColorConnected to:Default mapping:
LED2RedSCSystem Controller Status LED
LED3GreenZynq PLFPGA Done - active low


Is mapped to MIO7 after power up. After the Zynq PS has booted it can change the mapping of this LED. If SC can not enable power to the Zynq then this LED will remain under SC control. It is available to the user only after the power supplies have stabilized and the POR reset to the Zynq is released.


Is used by the SC as global status LED. The SC can show status information on this LED. Vin power is not required.


This green LED is connected to the FPGA Done pin which has an active low state. As soon as the Zynq is powered and the 3.3V I/O voltage is enabled, this LED will illuminate. This indicates that the Zynq PL is not configured. Once the Zynq PL has been configured the LED will go off.

During normal operation when the Zynq PL has been configured, the LED can be controlled from the FPGA fabric. Control of the LED in a user design requires the use of Xilinx startup primitive rather than a normal I/O primitive. If the startup primitive is not used then the LED will go off after configuration and remain off irrespectively of the user design. This LED can not be controlled by the SC.

This LED will not operate if the SC can not power on the 3.3V output rail that also powers the 3.3V circuitry on the module.

LED Status Codes

1OFFOFFONFatal power errorThis combination after power up is only possible in no sequencing compatibility mode were 3.3Vout is supplied externally. The 1.0V and 1.8V DC-DC supplies are forced on (NOSEQ=1), and the SC is not able to start (3.3Vin below 2.1V). This should never happen if the external power supplies are OK.
2OFFONOFFVIN missing (or EN1 low)3.3Vin is present, but the DC-DC supplies are not powered or 3.3Vin is below 3.05V. If the LEDs stay on in this state then 3.3Vout is not turned on, and the Zynq is kept in the POR state.
3OFF1/2 Blink Fast 4 HzONOKBoot mode selected is SPI Flash. This status remains after boot also if the LED settings are not changed and user is not controlling MIO7 and FPGA is not loaded.
4OFF1/2 Blink Slow 1 HzONOKBoot mode selected is SD Card. This status remains after boot also if the LED settings are not changed and user is not controlling MIO7 and FPGA is not loaded.
5MIO7 or user functionBlink or user functionOFFOKLED3 goes off when the FPGA is configured. NOTE: The FPGA design can control this LED too using STARTUPE2, so it may remain ON or be flashing when the FPGA is configured.
6ONSlow blink 0.5Hz, 1/8 on, 7/8 offOFFPowerdownEN1 input to the module is low. If sequencing is enabled in this mode, then all power supplies on the module are OFF.
7ONSlow blink 0.5Hz, 1/8 on, 7/8 offON
EN1 input to the module is low. Sequencing is disabled module is in reset state.
8ONONONResetPowered, RESIN input is active low or Bank B34 Supply Voltage is missing.

If green LED3 does not light up at least for short time at power then there is major problem with power supplies, FPGA core and aux voltages may be missing.

Appx. A: Change History and Legal Notices

Revision Changes

Document Change History

To get content of older revision  got to "Change History"  of this page and select older document revision number.

DateDocument RevisionCPLD Firmware RevisionSupported PCB RevisionAuthorsDescription


------Work in progress


------Initial release


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