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JS7688-core-board manual
v1.0 (2020.08.26)

Product overview

JS7688 core board module is a WIFI module based on MTK (Mediatek) MT7688AN SOC chip scheme launched by Hangzhou Jotale Technology Co., LTD.CPU frequency up to 580MHz, onboard optional 64MB DDR2 RAM/8MB Flash, 128MB DDR2 RAM/16MB Flash, 256MB DDR2 RAM/32MB Flash configuration, 150M WIFI, external leads USB 2.0 Host, GPIO, UART, I2S, I2C, SD card interface, SPI, PWM, Ethernet interface, WIFI antenna interface, etc..
This module is small in size, low in power consumption, low in heat, and stable in WIFI and network port transmission performance. Running OpenWRT (Linux) system can run stably for a long time. The peripheral circuit of the module is very simple. It only needs to add a 3.3V DC power supply to start the system and can be controlled through WIFI. The use of a gold-plated needle connection or stamp hole connection can be very stable fixed on the bottom plate.
It can be used in many applications such as smart homes, IP cameras, VOIP, remote shooting aircraft, remote monitoring systems, simple WEB network servers, simple FTP servers, remote download, remote vision cars, etc. We specially develop the motherboard for this core board, the composition JS7688 development board, and provides the detailed development information, facilitates the user to study, the development, the details please enter www.jotale.com website to view.

Product parameter

Product name JS7688-core-board
Product model JS7688_CORE_BOARD
Operating system OpenWrt (Linux)
CPU MT7688AN MIPS 24KEc
System frequency 580MHz
RAM 64MB/128MB/256MB DDR2 RAM
Flash 8MB/16MB/32MB Nor flash
Ethernet interface 5 x WAN/LAN 10/100M adaptive
USB interface 1 x USB 2.0 host
PCIE interface 1 x PCIE
UART interface UART0(debug by default), UART1, UART2
GPIO interface Total 40 (reused with other functions)
I2S x 1,support VOIP
I2C 1xI2C master
 SPI master 2 x SPI master(One of them is occupied by Flash and the other is free)
SPI slave 1 x SPI slave
PWM 4 x PWM
 

 Module size

Stamp hole version  38.5mm x 22mm x 2.8mm
Pin header version  

45mm x 31mm x 10mm

Pin interface Stamp hole、Pin header
Operating voltage 3.3V ±10%
Average power consumption 0.6W
Supply current capacity ≥500mA
Antenna interface 1 x IPEX
Operating temperature -20~60℃
Wireless protocol Support IEEE802.11 b/g/n
Wireless rate 1T1R, 150Mbps
RF power consumption ≤18dbm
Wireless distance ≤100 meters (open area)
Wireless working mode routing, AP, relay, bridge

Appearance and pin introduction

The JS7688 core board has two packaging forms available for customers to choose namely the “Stamp hole version” and “Pin header version”. Below are the photos of the real product and the packaging introduction.
2.1 Pin header version
2.1.1 Real photos

Jotale JS7688 Core Board Module - real photos

2.1.2 Pins introduction and product size

Jotale JS7688 Core Board Module - fig1

Pin introduction of JS7688-core-board pin header version

Pin Function 0 Function 1 Function 2 Function 3 comment
1 GND N/A N/A N/A Main power GND
2 GND N/A N/A N/A Main power GND
3 GND N/A N/A N/A Main power GND
4 VDD3V3 N/A N/A N/A Main power supply 3.3V DC
5 VDD3V3 N/A N/A N/A Main power supply 3.3V DC
6 VDD3V3 N/A N/A N/A Main power supply 3.3V DC
7 REF_CLK_O GPIO37 N/A N/A Default as GPIO, SYSTEM_LED
8 WDT_RST_N GPIO38 N/A N/A Default as GPIO, USER_KEY1
9 EPHY_LED4_N_JTRST_N GPIO39 w_utif_n[6] jtrstn_n Default as GPIO,  LAN_LED
10 EPHY_LED3_N_JTCLK GPIO40 w_utif_n[7] jtclk_n Default as GPIO, LAN2_LED
11 EPHY_LED2_N_JTMS GPIO41 w_utif_n[8] jtms_n Default as GPIO, USER_KEY2
12 EPHY_LED1_N_JTDI GPIO42 w_utif_n[9] jtdi_n Default as GPIO, LAN1_LED
13 EPHY_LED0_N_JTDO GPIO43 N/A jtdo_n Default as GPIO, WAN_LED
14 WLED_N GPIO44 N/A N/A Default as GPIO, RESET_FN_KEY
15 GND N/A N/A N/A GND
16 UART_TXD1 GPIO45 PWM_CH0 antsel[1] Internally connect 10K pull-up resistance to 3.3V, default as UART_TXD1
17 UART_RXD1 GPIO46 PWM_CH1 antsel[0] Default as UART_RXD1
18 I2S_SDI GPIO0 PCMDRX antsel[5] Default as I2S_SDI
19 I2S_SDO GPIO1 PCMDTX antsel[4] Internally connect 10K pull-down resistance to GND, default as I2S_SDO
20 I2S_WS GPIO2 PCMCLK antsel[3] Default as I2S_WS
21 I2S_CLK GPIO3 PCMFS antsel[2] Default as I2S_CLK
22 I2C_SCLK GPIO4 sutif_txd ext_bgclk Default as I2C_SCLK
23 I2C_SD GPIO5 sutif_rxd N/A Default as I2C_SD
24 SPI_CS1 GPIO6 REF_CLK_O N/A Internally connect 10K pull-down resistance to GND, default as SPI_CS1
25 VDD3V3_PROG N/A N/A N/A External Flash burner power
supply DC 3.3V input pin. Note: it is only necessary to connect when use the external flash burner. It is usually not connect
26 SPI_CLK GPIO7 N/A N/A Internally connect 10K pull-up resistance to 3.3V, default as SPI_CLK
27 GND N/A N/A N/A GND
28 SPI_MOSI GPIO8 N/A N/A Internally connect 10K pull-down resistance to GND, default as SPI_MOSI
29 SPI_MISO GPIO9 N/A N/A Default as SPI_MISO
30 GPIO11 GPIO11 REF_CLK_O PERST_N Default as REF_CLK_O
31 SPI_CS0 GPIO10 N/A N/A Default as SPI_CS0, used by the system for flash control, can be used for flash burning
32 UART_RXD0 GPIO13 N/A N/A Default as UART_RXD0, system debug uart port
33 UART_TXD0 GPIO12 N/A N/A Internally connect 10K pull-down resistance to GND, default as UART_TXD0, system debug UART port
34 MDI_R_P0_P N/A N/A N/A Ethernet 0 receives a positive port
35 GND N/A N/A N/A GND
36 GND N/A N/A N/A GND
37 MDI_R_P0_N N/A N/A N/A Ethernet 0 receives negative port
38 MDI_T_P0_N N/A N/A N/A Ethernet 0 transmit negative port
39 MDI_T_P0_P N/A N/A N/A Ethernet 0 transmit positive port
gateway mode IOT device mode
40 MDI_T_P1_N SPIS_CLK GPIO15 w_utif[1] PWM_CH1 Default as PWM_CH1
41 MDI_T_P1_P SPIS_CS GPIO14 w_utif[0] PWM_CH0 Default as PWM_CH0
42 MDI_R_P1_N SPIS_MOSI GPIO17 w_utif[3] UART_RXD2 Default as UART_RXD2
43 MDI_R_P1_P SPIS_MISO GPIO16 w_utif[2] UART_TXD2 Default as UART_TXD2
44 MDI_R_P2_N PWM_CH1 GPIO19 w_utif[5] SD_D6 Default as GPIO
45 MDI_R_P2_P PWM_CH0 GPIO18 w_utif[4] SD_D7 Default as GPIO
46 GND N/A N/A N/A GND
47 MDI_T_P2_P UART_TXD2 GPIO20 PWM_CH2 SD_D5 Default as PWM_CH2
48 MDI_T_P2_N UART_RXD2 GPIO21 PWM_CH3 SD_D4 Default as PWM_CH3
49 MDI_T_P3_P SD_WP GPIO22 w_utif[10] w_dbgin Default as SD_WP
50 MDI_T_P3_N SD_CD GPIO23 w_utif[11] w_dbgack Default as SD_CD
51 GND N/A N/A N/A GND
52 MDI_R_P3_N SD_D0 GPIO25 w_utif[13] w_jtdi Default as SD_D0
53 MDI_R_P3_P SD_D1 GPIO24 w_utif[12] w_jtclk Default as SD_D1
54 GND N/A N/A N/A GND
55 MDI_R_P4_P SD_CLK GPIO26 w_utif[14] w_jtdo Default as
SD_CLK
56 MDI_R_P4_N SD_CMD GPIO27 w_utif[15] dbg_uart_t Default as SD_CMD
57 MDI_T_P4_P SD_D3 GPIO28 w_utif[16] w_jtms Default as SD_D3
58 MDI_T_P4_N SD_D2 GPIO29 w_utif[17] w_jtrst_n Default as SD_D2
59 GND N/A N/A N/A GND
60 USB_N N/A N/A N/A USB negative port
61 USB_P N/A N/A N/A USB positive port

Note: When the chip is in “gateway mode”, the pin function of the associated network port multiplexing is unavailable. In this case, the pin function of these multiplexed pins is an ethernet port. While in “Internet of Things device mode”, the Ethernet function of these multiplexed pins is not available and other multiplexing functions are available.JS7688 pin header version and JS7628 pin header version pin is fully compatible in the common motherboard.
2.2 Stamp hole packaging
2.2.1 Real photos

Jotale JS7688 Core Board Module - real photos2

2.2.2 Pins introduction and product size

Jotale JS7688 Core Board Module - fig2

JS7688-core-board stamp hole version pins introduction

Pin Function 0 Function 1 Function 2 Function 3 comment
1 GND N/A N/A N/A Main power GND
2 GND N/A N/A N/A Main power GND
3 VDD3V3 N/A N/A N/A Main power supply 3.3V DC
4 VDD3V3 N/A N/A N/A Main power supply 3.3V DC
5 GND N/A N/A N/A GND
6 PCIE_TX0_N N/A N/A N/A PCIE transmit negative port
7 PCIE_TX0_P N/A N/A N/A PCIE transmit positive port
8 GND N/A N/A N/A GND
9 PCIE_RX0_P N/A N/A N/A PCIE receive positive port
10 PCIE_RX0_N N/A N/A N/A PCIE receive negative port
11 GND N/A N/A N/A GND
12 PCIE_CK0_N N/A N/A N/A PCIE clock negative port
13 PCIE_CK0_P N/A N/A N/A PCIE clock positive port
14 PERST_N GPIO36 N/A N/A Internally connect 10K pull-down resistance to GND,
default as GPIO
15 REF_CLK_O GPIO37 N/A N/A Default as GPIO, SYSTEM_LED
16 WDT_RST_N GPIO38 N/A N/A Default as GPIO, USER_KEY1, high level effective
17 EPHY_LED4_N_JTRST_N GPIO39 w_utif_n[6] jtrstn_n Default as GPIO, WLAN_LED
18 EPHY_LED3_N_JTCLK GPIO40 w_utif_n[7] jtclk_n Default as GPIO, LAN2_LED
19 EPHY_LED2_N_JTMS GPIO41 w_utif_n[8] jtms_n Default as GPIO, USER_KEY2, high-level effective
20 EPHY_LED1_N_JTDI GPIO42 w_utif_n[9] jtdi_n Default as GPIO, LAN1_LED
21 EPHY_LED0_N_JTDO GPIO43 N/A jtdo_n Default as GPIO, WAN_LED
22 WLED_N GPIO44 N/A N/A Default as GPIO, RESET_FN_KEY, high-level effective
23 GND N/A N/A N/A GND
24 UART_TXD1 GPIO45 PWM_CH0 antsel[1] Internally connect 10K pull-up resistance to 3.3V, default as UART_TXD1
25 UART_RXD1 GPIO46 PWM_CH1 antsel[0] Default as UART_RXD1
26 GND N/A N/A N/A GND
27 I2S_SDI GPIO0 PCMDRX antsel[5] Default as I2S_SDI
28 I2S_WS GPIO2 PCMCLK antsel[3] Default as I2S_WS
29 GND N/A N/A N/A GND
30 I2S_SDO GPIO1 PCMDTX antsel[4] Internally connect 10K pull-down resistance to GND, default as I2S_SDO
31 I2S_CLK GPIO3 PCMFS antsel[2] Default as I2S_CLK
32 GND N/A N/A N/A GND
33 I2C_SCLK GPIO4 sutif_txd ext_bgclk Default as I2C_SCLK
34 I2C_SD GPIO5 sutif_rxd N/A Default as I2C_SD
35 VDD3V3_PROG N/A N/A N/A External Flash burner power supply DC 3.3V
input pin. Note: it is only necessary to connect when use the external flash burner. It is usually not connect
36 GND N/A N/A N/A GND
37 SPI_CS1 GPIO6 REF_CLK_O N/A Internally connect 10K pull-down resistance to GND, default as SPI_CS1
38 SPI_CS0 GPIO10 N/A N/A Default as SPI_CS0,used by system for flash control, can be used for flash burning
39 SPI_MOSI GPIO8 N/A N/A Internally connect 10K pull-down resistance to GND, default as SPI_MOSI
40 SPI_CLK GPIO7 N/A N/A Internally connect 10K pull-up resistance to 3.3V, default as SPI_CLK
41 SPI_MISO GPIO9 N/A N/A Default as SPI_MISO
42 GPIO11 GPIO11 REF_CLK_O PERST_N Default as REF_CLK_O
43 UART_RXD0 GPIO13 N/A N/A Default as UART_RXD0,system debug uart port
44 UART_TXD0 GPIO12 N/A N/A Internally connect 10K pull-down resistance to GND, default as UART_TXD0, system debug uart port
45 GND N/A N/A N/A GND
46 MDI_R_P0_P N/A N/A N/A Ethernet 0 receive
positive port
47 MDI_R_P0_N N/A N/A N/A Ethernet 0 receives a negative port
48 MDI_T_P0_P N/A N/A N/A Ethernet 0 transmit positive port
49 MDI_T_P0_N N/A N/A N/A Ethernet 0 transmit negative port
50 GND N/A N/A N/A GND
gateway mode IOT device mode
51 MDI_T_P1_P SPIS_CS GPIO14 w_utif[0] PWM_CH0 Default as PWM_CH0
52 MDI_T_P1_N SPIS_CLK GPIO15 w_utif[1] PWM_CH1 Default as PWM_CH1
53 MDI_R_P1_P SPIS_MISO GPIO16 w_utif[2] UART_TXD2 Default as UART_TXD2
54 MDI_R_P1_N SPIS_MOSI GPIO17 w_utif[3] UART_RXD2 Default as UART_RXD2
55 GND N/A N/A N/A GND
56 MDI_R_P2_P PWM_CH0 GPIO18 w_utif[4] SD_D7 Default as GPIO
57 MDI_R_P2_N PWM_CH1 GPIO19 w_utif[5] SD_D6 Default as GPIO
58 MDI_T_P2_P UART_TXD2 GPIO20 PWM_CH2 SD_D5 Default as PWM_CH2
59 MDI_T_P2_N UART_RXD2 GPIO21 PWM_CH3 SD_D4 Default as PWM_CH3
60 GND N/A N/A N/A GND
61 MDI_T_P3_P SD_WP GPIO22 w_utif[10] w_dbgin Default as SD_WP
62 MDI_T_P3_N SD_CD GPIO23 w_utif[11] w_dbgack Default as SD_CD
63 MDI_R_P3_P SD_D1 GPIO24 w_utif[12] w_jtclk Default as SD_D1
64 MDI_R_P3_N SD_D0 GPIO25 w_utif[13] w_jtdi Default as SD_D0
65 GND N/A N/A N/A GND
66 MDI_R_P4_P SD_CLK GPIO26 w_utif[14] w_jtdo Default as SD_CLK
67 MDI_R_P4_N SD_CMD GPIO27 w_utif[15] dbg_uart_t Default as SD_CMD
68 MDI_T_P4_P SD_D3 GPIO28 w_utif[16] w_jtms Default as SD_D3
69 MDI_T_P4_N SD_D2 GPIO29 w_utif[17] w_jtrst_n Default as SD_D2
70 GND N/A N/A N/A GND
71 USB_P N/A N/A N/A USB positive port
72 USB_N N/A N/A N/A USB negative port
73 GND N/A N/A N/A GND

Note: When the chip is in “gateway mode”, the pin function of the associated network port multiplexing is unavailable. In this case, the pin function of these multiplexed pins is an ethernet port. While in “Internet of Things device mode”, the Ethernet function of these multiplexed pins is not available and other multiplexing functions are available.JS7688 pin header version and JS7628 pin header version pin fully compatible in the common motherboard.

2.2.3 Recommend package

Jotale JS7688 Core Board Module - fig3

Note: “JS7688_convert_board_xxxx.PcbLib” (XXXX is version number) JS7688 module PCB package the library is provided inside。

Baseboard reference design

3.1 Power circuit
The power supply voltage of the scoreboard is 3.3V and the average current is about 185mA. In order to ensure the stable operation of the score board, a current of at least 500mA should be reserved for the module (depending on the actual application). The figure below is the design of 3.3V power supply of JS7628 baseboard

Jotale JS7688 Core Board Module - fig4

MP1482 stabilized power supply chip is used in the figure above, which can reach 2A output current. Users can choose whether to use this model or not according to the actual situation. It is not recommended to use an “LDO chip” power supply, such as AMS1117, although the circuit design of this kind of chip is simple, the high current working efficiency is too low, and high heat, it is easy to cause the system power supply shortage, thus leading to the instability of the system.

3.2 About GPIO ports
The INPUT and output voltage of the GPIO pin of MT7628/MT7688 is 3.3V. Some GPIO pins are pull-up or pull-down inside the module to configure the system for MT7628/MT7688 startup. Note that when the board is started, the GPIO pin labeled “pull up” in the “pin introduction” should not be externally forced to pull down to a low level, and the GPIO pin labeled “pull-down” should not be externally forced to pull up to a high level, otherwise, the system may be unable to work normally. Other GPIO can be used according to the ordinary GPIO port.

3.3 Core board minimum system
The user only needs to connect the pins “GND” and “VDD3V3” of the core board to supply power to the scoreboard, and connect the three key pins “WDT_RST_N”,  “EPHY_LED2_N_JTMS” and “WLED_N” with 10K pull-down resistance to the ground, and the system can work normally. This module generally does not need to add heat sinks, but in order to improve the heat dissipation efficiency of the system, please try to connect all “GND” pins of the module to the bottom plate “GND” pins designed by the reader, so as to achieve better heat dissipation effect. Other pins, such as debug serial port, network port, etc., can be added according to the user’s own needs. If you don’t need them, just not connect them. Readers can refer to“JS7628_base_board_xxxxx.pdf”(xxxxx is version number)base board schematic for designing。

The temperature when reflowing

If the customer needs to design the baseboard with the JS7688 stamp hole version module through the reflow welding machine, pay attention to the reflow welding peak emperature do not exceed 240 ℃, otherwise, it may cause damage to the JS7688 stamp hole module.

Revision history

version time Modify description
v1.0 2020.08.27 The initial version of the JS7688-core-board manual with English. Based on Chinese manual v1.6

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 received, including 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 to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates 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 harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the 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.

The WIFI Module is designed to comply with the FCC statement. FCC ID is 2AXEE-JS7688. The host system using the WIFI Module should have a label indicating it contains the modular’s FCC
ID :2AXEE-JS7688. This radio module must not be installed to colocate and operate simultaneously with other radios in the host system additional testing and equipment authorization may be required to operate simultaneously with other radios.
The WIFI module is designed for a compact PCB design.It should be installed and operated with the host or other minimum distance of 20 centimeters between the radiator and your body.” To comply with FCC regulations limiting both maximum RF output power and human exposure to RF radiation, the maximum antenna gain including cable loss in a mobile-only exposure condition must not exceed 5dBi in the 2.4G band. The WIFI Module and its antenna must not be co-located or operating in
conjunction with any other transmitter or antenna within a host device.
This module integrates an IPEX antenna interface, the user needs to purchase and install the antenna according to the instructions.

Notice to OEM integrator
The WIFI module is designed for a compact PCB design.It should be installed and operated with a laptop. OEM can install the module into the host through the module’s USB port, but it should be noted that the module’s swipe port needs to be correctly installed on the surface to ensure the normal operation of the NFC function.
The end-user manual shall include all required regulatory information/warning as shown in this manual. The OEM integrator is responsible for testing their end-product for any additional compliance requirements required with this module installed.
The device must be professionally installed The intended use is generally not for the general public.lt is generally for industry/commercial use. The connector is within the transmitter enclosure and can only be accessed by disassembly of the transmitter that is not normally required, the user has no access to the connector. Installation must be controlled. Installation requires special training This device complies with Part 15, Subpart C, Section 15.247 of the FCC Rules.

Jotale logo
JS7688-core-board manual
Hangzhou Jotale Technology Co., Ltd
www.jotale.com

Documents / Resources

Jotale JS7688 Core Board Module [pdf] User Manual
JS7688, 2AXEE-JS7688, 2AXEEJS7688, JS7688, Core Board Module, Core Board, Board Module, JS7688, Module

References

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