SOM7981 Based System On Module
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Specifications
- Product Name: SOM7981 System-on-Module
- Version: V1.0
- Chipsets: MT7981BA and MT7976C
- Wi-Fi Features:
- IEEE 802.11 Wi-Fi 6 (a/b/g/n/ac/ax)
- Wi-Fi Frequency: 2.4GHz, 5GHz
- Antenna Configuration: 2T3R
- Data Throughput: 3Gbps
Product Usage Instructions
1. Hardware Overview
The SOM7981 System-on-Module is built around MT7981BA and
MT7976C chipsets. It features multiple antennas for both 2.4GHz and
5GHz Wi-Fi frequencies.
2. Interface Details
Left Connector (Top View)
The left connector of the SOM7981 module provides various
interfaces accessible through pins. Some key interfaces
include:
- UART Communication
- JTAG Interface
- USB Ports
- PCI Express (PCIe) Connections
- SPI Interface
- I2C Communication
Right Connector (Top View)
The right connector of the SOM7981 module offers additional
interfaces like:
- UART Communication
- I2C Communication
- SPI Interface
- GPIOs for Reset and Wake-up functionalities
- Ethernet Connectivity
3. Power Supply
The module requires a stable power supply of 12V for proper
operation. Ensure a reliable power source is connected to the
designated power input pins.
4. Additional Resources
For detailed technical information on each interface and pin
functionality, refer to the MT7981BA Data Sheet and Reference
Manual provided by the manufacturer.
Frequently Asked Questions (FAQ)
Q: What is the maximum data throughput supported by the Wi-Fi
module?
A: The SOM7981 supports a data throughput of up to 3Gbps.
Q: How many antennas are available for the Wi-Fi
connection?
A: The SOM7981 module features a 2T3R antenna configuration for
optimal wireless connectivity.
Q: What are the key interfaces available on the left
connector?
A: The left connector provides interfaces such as UART, JTAG,
USB, PCIe, SPI, and I2C for versatile connectivity options.
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SOM7981 USER MANUAL
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SOM7981 USER MANUAL
V1.0
MT7981BA and MT7976C Based System-on-Module
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SOM7981 USER MANUAL
Revision History
Version Draft
Description Initial Release
Date 08/04/2024
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SOM7981 USER MANUAL
Contents
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SOM7981 USER MANUAL
1. Introduction
SOM7981 is an advanced System on Module (SoM) equipped with a MediaTek® MT7981BA processor and a powerful Wi-Fi 6 dual-band radio. This compact SOM blends a high-performance CPU with an extended-range radio module, making it perfect for Wi-Fi and IoT applications. It offers a tiny,hackable linux and OpenWrt platform for VPN router,IoT,smart home and more.
Core features of the SOM7981 module include: MediaTek® MT7981BA SoC
– ARM® dual-core Cortex®-A53 CPU running at 1400Hhz – HW NAT – HW QoS 512MB/1GB DDR4 memory Up to 256MB SPI NAND flash One Gigabit Ethernet (10/100/1000 Mbps) One HSGMII interface for 2.5G Ethernet (10/100/1000/2500 Mbps On-chip encryption
Hardware Interfaces: One HSGMII interface for 2.5G Ethernet (10/100/1000/2500) Mbps One Gigabit Ethernet (10/100/1000 Mbps) 3x UART 3x SPI (50 Mbit/s, including 3 with full duplex I2S audio class accuracy) 1x PCM (stereo audio: I2S, PDM, SPDIF Tx) 2x SDMMC up to 8-bit (SD / e·MMCTM / SDIO) USB 3.0 host PCIe Gen2 1-linex1 multiplexed with USB 3.0 interface 30+ GPIO multiplexed with our functions
Wi-Fi features: IEEE 802.11 Wi-Fi 6 (a/b/g/n/ac/ax) Wi-Fi Frequency 2.4GHz, 5GHz Antenna 2T3R Data Throughput 3Gbps
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SOM7981 USER MANUAL
2. Hardware
The module is built around MT7981BA and MT7976C.
2.4G+5G WiFi Antenna1 2412-2462MHz/ 5180-5825MHz
2.4G+5G WiFi Antenna2 2412-2462MHz/ 5180-5825MHz
5G WiFi Antenna3 5180-5825MHz
Y3 40MHz
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SOM7981 USER MANUAL
3. Interface
The following sections list the interfaces available on the SoM7981 and details the module pins used to interact with and control each interface. See the MT7981BA Data Sheet and Reference Manual for complete functional descriptions, programming guidelines and register listings for each of these blocks.
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SOM7981 USER MANUAL 3.1 PINOUT of LEFT CONNECTOR(top view)
PIN NO.
Func.0
Func.1
Func.2
Func.3
Func.4
GND
1
GND
3
1.8V_OUT 5
1.8V_OUT 7
1.8V_OUT 9
1.8V_OUT 11
1.8V_OUT 13
1.8V_OUT 15
GND
17
GND
19
GND
21
GND
23
GND
25
2
GND
4
6
8
10
12
14
16
18 SYS_RST#
20 GND
22 PCIE_RST#
24 GND
26 PCIE_CLKN
GPIO3 PCIE_RST#
27
28 PCIE_CLKP
29
30 GND
31
32 SSUSB_RXN
33
34 SSUSB_RXP
35
36 GND
37
38 SSUSB_TXN
39
40 SSUSB_TXP
41
42 GND
43
44 USB20_DM
45
46 USB20_DP
47
48 GND
49
50 USB_VBUS
51
52 WF5G_LED
53
54 WF2G_LED
GPIO14 USB_VBUS GPIO35 WF5G_LED GPIO34 WF2G_LED
PWM1 PCIE_WAKE# PCIE_CLKREQ
55
56 GND
57
58 SYS_WDT
GPIO2 SYS_WDT
59
60 POR_RST#_1V8
61
62 GND
63
64 JTAG_JTDO
GPIO4 JTAG_JTDO
65
66 JTAG_JTDI
GPIO5 JTAG_JTDI
UART2_RXD UART2_TXD
67
68 JTAG_JTMS
GPIO6 JTAG_JTMS
UART2_CTS
69
70 JTAG_JTCK
GPIO7 JTAG_JTCK
UART2_RTS PWM2
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SOM7981 USER MANUAL
GND GND GND GND GND GND 12V_IN 12V_IN 12V_IN 12V_IN 12V_IN 12V_IN GND
71
72
JTAG_JTRST#
GPIO8 JTAG_JTRST#
73
74 GND
75
76 WO_JTDO
GPIO9 WO_JTDO
77
78 WO_JTDI
GPIO10 WO_JTDI
79
80 WO_JTMS
GPIO11 WO_JTMS
81
82 WO_JTCK
GPIO12 WO_JTCK
83
84 WO_JTRST#
GPIO13 WO_JTRST#
PWM0
85
86 GND
87
88 SPI2_CS
GPIO29 SPI2_CS
UART1_RTS
89
90 SPI2_MISO
GPIO28 SPI2_MISO
UART1_CTS
91
92 SPI2_MOSK
GPIO27 SPI2_MOSK
UART1_TXD
93
94 SPI2_CLK
GPIO26 SPI2_CLK
UART1_RXD
95
96 SPI2_WP
GPIO31 SPI2_WP
WF5G_LED
97
98 SPI2_HOLD
GPIO30 SPI2_HOLD
WF2G_LED
99
100 GND
GBE_LED0 GBE_LED1
PCM_TX PCM_RX PCM_CLK PCM_FS PCM_MCK
I2C_SDA I2C_SCL
Table1: left connector
3.2 PINOUT of RIGHT CONNECTOR(top view)
Func.4
Func.3
Func.2
Func.1
Func.0
PIN NO.
PWM1
GND
1
2
GND
3
4
5
6
GND
7
8
9
10
11
12
GND
GND
13
14
GPIO1 RST#
15
16
GPIO0 WPS#
17
18
GND
GND
19
20
UART0_TXD GPIO33 UART0_TXD 21
22
UART0_RXD GPIO32 UART0_RXD 23
24
GND
GND
25
26
I2C_SDA
SMI_MDIO
GPIO37 SMI_MDIO
27
28
I2C_SCL
SMI_MDC
GPIO36 SMI_MDC
29
30
GND
GBE_INT#
GPIO38 GBE_INT#
31
32
GND
33
34
GPIO39 GBE_RST#
35
36
GND
EMMC_RST# PWM0
GPIO15 PWM0
37
38
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SOM7981 USER MANUAL
GND
39
40
UART2_RTS EMMC_CLK
SPI1_CS
GPIO25 SPI1_CS
41
42
GND
UART2_CTS EMMC_CMD SPI1_MISO
GPIO24 SPI1_MISO
43
44
UART2_TXD EMMC_DAT7 SPI1_MOSI
GPIO23 SPI1_MOSI
45
46
UART2_RXD EMMC_DAT6 SPI1_CLK
GPIO22 SPI1_CLK
47
48
GND
GND
49
50
UART1_RTS
EMMC_DAT3 SPI0_CS
GPIO19 SPI0_CS
51
52
UART1_CTS
EMMC_DAT2 SPI0_MISO
GPIO18 SPI0_MISO
53
54
GND
UART1_TXD
EMMC_DAT1 SPI0_MOSI
GPIO17 SPI0_MOSI
55
56
UART1_RXD
EMMC_DAT0 SPI0_CLK
GPIO16 SPI0_CLK
57
58
EMMC_DAT5 SPI0_WP
GPIO21 SPI0_WP
59
60
EMMC_DAT4 SPI0_HOLD GPIO20 SPI0_HOLD
61
62
GND
63
64
HSGMII_RXP 65
66
HSGMII_RXN 67
68
GND
69
70
HSGMII_TXN 71
72
GND
HSGMII_TXP 73
74
GND
GND
75
76
GND
NET1_TRXP3 77
78
GND
NET1_TRXN3 79
80
GND
GND
81
82
GND
NET1_TRXP2 83
84
3.3V_OUT
NET1_TRXN2 85
86
3.3V_OUT
GND
87
88
3.3V_OUT
NET1_TRXP1 89
90
3.3V_OUT
NET1_TRXN1 91
92
3.3V_OUT
GND
93
94
3.3V_OUT
NET1_TRXP0 95
96
3.3V_OUT
NET1_TRXN0 97
98
3.3V_OUT
GND
99
100
GND
Table2: Right connector
3.3 Power supply Signals
When developing a carrier board for SOM7981,the power supply signals should be considered first.
All GND signals should be connected to system ground directly. 12V_IN , main power supply of the module. USB_VBUS, 5V USB power supply. 3.3V_OUT, on board 3.3V DC-DC output .
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SOM7981 USER MANUAL
3.4 System Signals
3.4.1 SYS_RST#
It is a directional, open drain signal, pulled up to the 3.3V_OUT. The signal is used as global module reset. When driven low by the carrier board, it reset the whole module.When module power sequence is complete,it can be used as carrier board supply enable, used to ensure proper power on/off sequencing between module and carrier board power supplies,an 4.7k resistor is used to pull-up to the 3.3V_OUT.
3.4.2 Boot mode and storage
The SPI-NAND boot is the first boot mode in boot sequence(The SPI-NAND chip has been equipped in the SOM when shipped out). But if the customer need the eMMC as mass storage,you may change the boot mode to eMMC and need to place the eMMC on the carrier PCB board.
SPI1_MISO SPI1_CS PWM0
U1A
SPI0_CLK SPI0_MOSI SPI0_MISO
SPI0_CS SPI0_HOLD
SPI0_WP SPI1_CLK SPI1_MOSI
R9
22R R0402
R3 R4 R5 R6
22R/nc R0402 eMMC_DATA0 22R/nc R0402 eMMC_DATA1 22R/nc R0402 eMMC_DATA2 22R/nc R0402 eMMC_DATA3
A3 A4 DATA0 A5 DATA1 B2 DATA2
C6 VCCQ1 M4 VCCQ2 N4 VCCQ3 P3
R1 R2 R7 R8
22R/nc R0402 eMMC_DATA4 22R/nc R0402 eMMC_DATA5 22R/nc R0402 eMMC_DATA6 22R/nc R0402 eMMC_DATA7
B3 DATA3 B4 DATA4 B5 DATA5 B6 DATA6
DATA7
VCCQ4 P5 VCCQ5
E6 VCC1 F5 VCC2 J10
eMMC_CMD
M5
VCC3 K9
CMD
VCC4
R10
22R R0402
eMMC_CLK
M6 CLK
J5 VSS1 A6
R11
22R R0402
eMMC_RSTB
K5 RST_n
VSS2 C4 VSS3 E7
C2
VSS4 G5
VDDi
VSS5 H10
1
2
1
2
1
R58 4.7K R0402
R59 4.7K R0402
R60 4.7K R0402
C7 1uF C0402
H5
VSS6
Data Strobe
K8
E9
VSSQ1 N2
E10 VSF1
VSSQ2 N5
F10 VSF2
VSSQ3 P4
K10 VSF3
VSSQ4 P6
2
VSF4
VSSQ5
3.3VD
EMMC_B153_2L BGA153_13RX11R5X0R9_2L
C4 100nF
10V C0402
C5 100nF
10V C0402
C2 100nF
10V C0402
C6 100nF
10V C0402
C3 100nF
10V C0402
C1 100nF
10V C0402
3.3VD
3.3VD
NOTE: The SPI0 and eMMC can’t be used at the same time. If you want to use the eMMC as system storage,the SPI-NAND pre-solded chip should be removed
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SOM7981 USER MANUAL
3.4.3 EthernetS
The MT7981BA integrates an Ethernet PHY internally with 10/100/1000 BASE-T IEEE 802.3 compliant .
Name
Direction
Typ e
NET1_TRXP0 NET1_TRXN0
Bidirectional MDI
NET1_TRXP1 NET1_TRXN1 Bidirectional MDI
NET1_TRXP2 Bidirectional MDI NET1_TRXN2
NET1_TRXP3 NET1_TRXN3
Bidirectional MDI
GBE_LED_ACT Output
GBE_LED_LINK Output
Description
MDI Data0
MDI Data1
MDI Data2
MDI Data3 Ethernet Activity LED(yellow) Link LED (green) enable,only lighted in 1000 Mbps mode
NET1_TRXP0 NET1_TRXN0 NET1_TRXP1 NET1_TRXN1
NET1_TRXP2 NET1_TRXN2 NET1_TRXP3 NET1_TRXN3
U9 B0524P SON10_2R50X1R00X0R50
1 IN1
2 IN2
4 IN3
5 IN4
10 OUT1
9 OUT2
7 OUT3
6 OUT4
3 8 GND1
GND2
U10 B0524P SON10_2R50X1R00X0R50
1 IN1
2 IN2
4 IN3
5 IN4
10 OUT1
9 OUT2
7 OUT3
6 OUT4
10 GND
15 16 SH1
SH2
CN1
13 LEDYC
NET1_TRXP0 NET1_TRXN0 NET1_TRXP1 NET1_TRXN1 NET1_TRXP2 NET1_TRXN2 NET1_TRXP3 NET1_TRXN3
2 3 TRD1+ 4 TRD17 TRD2+ 5 TRD26 TRD3+ 8 TRD39 TRD4+
TRD4-
LEDYA 14 R0402 330R
J1 J2 J3 J4 J5 J6 J7 J8
R37
1 TRDCT1/2/3/4
12 LEDGC
C36 100nF C0402
11 R0402 330R R41 LEDGA LPJG0806EBNL
JTAG_JTRST_N 3.3VD
W O_JTRST_N 3.3VD
3 8 GND1
GND2
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SOM7981 USER MANUAL
4.Electrical specifications 4.1 Recommended Operation Conditions
Symbol
12V_IN 3.3V_OUT 1.8V_OUT I/O pins
Comments
Min Typical Max Uint
Main power supply
4.5
12V
Main 3.3V power out put
3.0
3.3
Main 1.8V power out put
1.6
1.8
Other GPIO with specified -0.3
3.3
16
V
3.6
V
2.0
V
3.6
V
Note: 1. All GPIO pins should be powered after VDD_3V3_OUT 2. The total current of VDD_3V3_OUT should under 1.0A.
5. Mechanical Drawings(TBD) 6. Application examples (TBD)
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SOM7981 USER MANUAL
OEM integration instructions:
This device is intended only for OEM integrators under the following conditions: The transmitter module may not be co-located with any other transmitter or antenna. The module shall be only used with the external antenna(s) that has been originally tested and certified with this module. As long as the conditions above are met, further transmitter test will not be required. However, the OEM integrator is still responsible for testing their end-product for any additional compliance requirements required with this module installed (for example, digital device emissions, PC peripheral requirements, etc.). Validity of using the module certification: In the event that these conditions cannot be met (for example certain laptop configurations or co-location with another transmitter), then the FCC authorization for this module in combination with the host equipment is no longer considered valid and the FCC ID of the module cannot be used on the final product. In these circumstances, the OEM integrator will be responsible for re-evaluating the end product (including the transmitter) and obtaining a separate FCC authorization. End product labeling: The final end product must be labeled in a visible area with the following: “Contains Transmitter Module FCC ID: 2BKE9-SOM7981”. Information that must be placed in the end user manual: The OEM integrator has to be aware not to provide information to the end user regarding how to install or remove this RF module in the user’s manual of the end product which integrates this module. The end user manual shall include all required regulatory information/warning as show in this manual. Integration instructions for host product manufacturers according to KDB 996369 D03 OEM Manual v01 2.2 List of applicable FCCrules FCC Part 15 Subpart C 15.247 & 15.207 & 15.209 & 15.407 2.3 Specific operational useconditions The module WiFi Module is a module with WIFI 2.4G / WIFI 5G function. Operation Frequency: WIFI 2.4G:2412~2462MHz WIFI 5G:5150 MHz~5250MHz; 5250MHz~5350MHz; 5470MHz~5725MHz; 5725MHz ~5850MHz Type: WIFI 2.4G: External Antenna; Gain: Antenna 1: 4.3dBi; Antenna 2: 4.3dBi WIFI 5G: External Antenna; Gain:Antenna 1:5.16dBi; Antenna 2:5.16dBi; Antenna 3:5.16dBi The module can be used for mobile or applications with the maximum ; The host manufacturer installing this module into their product must ensure that the final composit product complies with the FCC requirements by a technical assessment or evaluation to the FCC rules, including the transmitter operaition. The host manufacturer has to be aware not to provide information to the end user regarding how to install or remove this RF module in the user’s manual of the end product which integrates this module. The end user manual shall include all required regulatory information/warning as show in this manual.
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SOM7981 USER MANUAL
2.4 Limited module procedures Not applicable. The module is a Single module and complies with the requirement of FCC Part 15.212. 2.5 Trace antennadesigns Not applicable. The module has its own antenna, and doesn’t need a host’s printed board microstrip trace antenna etc. 2.6 RF exposureconsiderations The module must be installed in the host equipment such that at least 20cm is maintained betweenthe antenna and users’ body; and if RF exposure statement or module layout is changed, then the host product manufacturer required to take responsibility of the module through a change in FCC ID or new application. The FCC ID of the module cannot be used on the final product. In these circumstances, the host manufacturer will be responsible for reevaluating the end product (including the transmitter) and obtaining a separate FCC authorization. 2.7 Antennas Antenna Specification are as follows: Type: WIFI 2.4G: External Antenna; Gain: Antenna 1: 4.3dBi; Antenna 2: 4.3dBi WIFI 5G: External Antenna; Gain:Antenna 1:5.16dBi; Antenna 2:5.16dBi; Antenna 3:5.16dBi This device is intended only for host manufacturers under the following conditions: The transmitter module may not be co-located with any other transmitter or antenna; The module shall be only used with the internal antenna(s) that has been originally tested and certified with this module. The antenna must be either permanently attached or employ a ‘unique’ antenna coupler. As long as the conditions above are met, further transmitter test will not be required. However, the host manufacturer is still responsible for testing their end-product for any additional compliance requirements required with this module installed (for example, digital device emissions, PC peripheral requirements, etc.). 2.8 Label and complianceinformation Host product manufacturers need to provide a physical or e-label stating “Contains FCC ID:2BKE9-SOM7981″with their finished product. 2.9 Information on test modes and additional testingrequirements Data transfer module demo board can control the EUT work in RF test mode at specified test channel. Additional testing, Part 15 Subpart B disclaimer. The module without unintentional-radiator digital circuit, so the module does not required an evaluation by FCC Part 15 Subpart B. The host should be evaluated by the FCC Subpart B. 2.10 Additional testing, Part 15 Subpart Bdisclaimer The modular transmitter is only FCC authorized for FCC Part 15 Subpart C 15.247 & 15.207 & 15.209 & 15.407 and that the host product manufacturer is responsible for compliance to any other FCC rules that apply to the host not covered by the modular transmitter grant of certification. If the grantee markets their product as being Part 15 Subpart B compliant. (when it also contains unintentional-radiator digital circuity), then the grantee shall provide a notice stating that the final host product still requires Part 15 Subpart B compliance testing with the modular transmitter installed.
Antenna information:
Manufacturer:ShenZhen XinErSheng Technology Co.,Ltd Model:SFANT12E13352
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SOM7981 USER MANUAL
FCC STATEMENT : This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) this device may not cause harmful interference, and (2) this device must accept any interference receivedincluding interference that may cause undesired operation.Any changes or modifications not expressly approved by the party responsible for compliance could void the user’s authority to operate the equipment. NOTE: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generate, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmfu interference to radio or television reception, which can be determined by turning the equipment off and on, the user is ncouraged to try to correct the interference by one or more of the following measures: — Reorient or relocate the receiving antenna. interference by one or more of the following measures: — Reorient or relocate the receiving antenna. — Increase the separation between the equipment and receiver. — Connect the equipment into an outlet on a circuit different from that to which the receiver is connected. — Consult the dealer or an experienced radio/TV technician for help. This equipment complies with FCC radiation exposure limits set forth for an uncontrolled environment. This equipment should be installed and operated with minimum distance 20cm between the radiator & your body.
Changes or modifications not expressly approved by the party responsible for compliance could void the user’s authority to operate the equipment. Operations in the 5.15-5.35GHz band are restricted to indoor usage only.
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