WF121 Wi-Fi MODULE DATA SHEET Tuesday, 14 February 2017 Version 2.
VERSION HISTORY Version Comment 1.0 First version 1.1 FCC and IC information added 1.2 WF121-N layout guide 1.3 Added power consumption measurements, regulatory info and some corrections 1.4 Added unassociated idle consumption and a chapter about power saving modes 1.4.1 Added CE information 1.4.2 Removed details from the regulatory info 1.4.3 Corrected typos in the pad function tables 1.4.4 Reduced the list of supported coexistence schemes 1.4.
1.5.4 Added USB example schematic 1.5.5 Corrections to Firmware section 1.5.6 Noted UART channel limitations, SPI BGAPI limitations 1.5.7 Correction to Reset chapter 1.5.8 Maximum SPI data rate updated 1.5.9 Added notes on Ethernet and 32kHz clock sections 1.5.10 Added a note on UART host bus flow control and clarified SPI host bus notify signal description 1.5.11 Corrected pinout drawing, TX power table 2.0.
TABLE OF CONTENTS 1 Design guidelines ..........................................................................................................................................7 2 Ordering Information......................................................................................................................................8 3 Pinout and Terminal Descriptions .................................................................................................................9 4 Packaging .......
13 RF Characteristics ................................................................................................................................. 32 14 Physical dimensions .............................................................................................................................. 34 15 Layout guidelines ................................................................................................................................... 35 15.1 WF121-E ............................
DESCRIPTION KEY FEATURES: WF121 is a self-contained Wi-Fi module providing a fully integrated 2.4GHz 802.11 b/g/n radio and a 32-bit microcontroller (MCU) platform, making it an ideal product for embedded applications requiring simple, lowcost and low-power wireless TCP/IP connectivity. WF121 also provides flexible interfaces for connecting to various peripherals. WF121 allows end user applications to be embedded onto the on-board 32-bit microcontroller using a simple BGScriptTM scripting.
1 Design guidelines Silicon Labs Page 7 of 45
2 Ordering Information Product code Description WF121-A WF121 module with integrated antenna, 500 units per Reel. WF121-E WF121 module with U.FL connector, 500 units per Reel. WF121 module with RF pin. WF121-N Non-standard product, so minimum order quantity applies. Please contact sales through: www.silabs.com DKWF121 WF121 development kit Note: Modules with order code ending in –v1 are sold as engineering samples, while those with code –v2 are production units.
3 Pinout and Terminal Descriptions Figure 1: WF121 pinout Silicon Labs Page 9 of 45
Pad number Function Description 9 VDD_3.3V Module power supply 8 VDD_PA 1, 16, 26, 45, 48, 50 GND 51 GNDPAD 40 Not Connected 49 ANT 25 VBUS USB VBUS input 13 MCLR Module reset, also used for programming using a Microchip tool.
PAD# GPIO Ethernet Timer 2 RB15 CN12 I2C SPI UART EMDC OCFB 3 RE0 ERXD1 4 RE1 ERXD0 5 RE2 ECRSDV 6 RE3 EREFCLK 7 RE4 ERXERR 10 RE5 ETXEN 11 RE6 ETXD0 12 RE7 ETXD1 14 15 17 USB Analog 18 RF3 19 RB14 SS4 nU2CTS SCK4 nU2RTS C1OUT E AN1 PGEC1 AN0 PGED1 AN8 OTG_ID AN14 20 RB13 AN13 TDI 21 RB12 AN12 TCK 22 RB11 AN11 TDO 23 RB10 AN10 TMS 24 RB5 CN 7 27 RG3 (input) D- 28 RG2 (input) D+ 29 RD3 30 RC12 31 RC15 32 RD2 33 34 35 36 37 3
4 Packaging W0 W1 45.0 +/-0.5 50.0 +/- 1.
Thickness (T) 0.061 mm Width (W) 37.5 mm +/-+0.
Unit: mm Figure 5: Tape Information Silicon Labs Page 14 of 45
5 5.1 Power control Power supply requirements WF121 consists of two separate internal blocks, the microcontroller and the radio part. The blocks have separate supply voltage inputs and the microcontroller can disable the radio part supply internally. WF121 is designed to operate with a 3.3V nominal input voltage supplied to the two supply inputs. The VDD_3.3V pad can be fed with a voltage between 2.3V and 3.6V and is used to power the internal microcontroller. However, when the VDD_3.3V line is below 3.
5.3 Reset WF121 can be reset by the MCLR-pin (active low), system power up or the internal brown-out detector.
6 6.1 Interfaces General Purpose I/O pins To see which GPIOs are multiplexed with which features, please refer to Table 2. WF121 contains a number of pads that can be configured to be used as general purpose digital IO’s, analog inputs or for various built-in functions. Provided functions include a Full Speed USB-OTG port, three I2C-ports, two SPI-ports, two UART’s, Ethernet MAC with RMII connection and various timer functions. Some of the pads are 5V tolerant.
6.
Other functions are present on the same pins; please refer to Table 2 for details. 6.
6.6 Analog inputs Pad number Function 2 AN15 14 AN1 15 AN0 17 AN8 19 AN14 20 AN13 21 AN12 22 AN11 23 AN10 24 AN5 Table 7: ADC pads The microcontroller provides a 10-bit Analog to digital converter (ADC) with sampling speeds up to 1MSps. The measurement can be done on any of the input pins listed in the table above. 6.
6.8 RF Debug Interface Pad number Pad function Description 52 SPI_MISO RF Debug data out 53 SPI_CLK RF Debug clock 54 SPI_MOSI RF Debug data in 55 SPI_CS RF Debug chip select Table 9: RF Debug SPI pads Four pads are provided for the debug interface of the WiFi chipset in the module bottom. This is meant for RF calibration and testing during module production and product certification measurements.
6.10 32.768 kHz External Reference Clock Pad number Function Description 33 SOSCI External 32.768 kHz crystal input 34 SOSCO External 32.768 kHz crystal output Table 11: Slow clock crystal pads The module contains integrated RC oscillators for sleep timing, one in the WiFi chipset, one in the CPU. The sleep clocks are used to periodically wake up the module while in power save modes. If more accurate timing is required, an external 32.
7 Block diagram Silicon Labs Page 23 of 45
8 Example schematics Figure 6: Minimal system required for UART host connection Figure 7: Recommended connections as a USB device.
9 9.1 802.11 Radio Wi-Fi Receiver The receiver features direct conversion architecture. Sufficient out-of-band blocking specification at the Low Noise Amplifier (LNA) input allows the receiver to be used in close proximity to GSM and WCDMA cellular phone transmitters without being desensitized. High-order baseband filters ensure good performance against in-band interference. 9.2 Wi-Fi Transmitter The transmitter features a direct IQ modulator.
10 Firmware WF121 incorporates firmware which implements a full TCP/IP stack and Wi-Fi management. Exact features will depend on the firmware version used. Please see the documentation of the firmware for exact details. There are two main ways to use the module: Host controlled and script controlled. Host controlled means an external host is physically connected to the module and it sends simple commands to the module and one of several different host interfaces can be used.
11 Host interfaces 11.1 UART The module can be controlled over the UART interface. In order for the communication to be reliable, hardware flow control signals (RTS and CTS) must be present between the host and the module. When using high UART transfer speeds (between 1 and 20Mbps), an external crystal is required on OSC1/OSC2 for sufficient clock accuracy. When using WF121 UART in transparent mode, we highly recommend using RTS/CTS flow control to avoid the possibility of losing data. 11.
12 Electrical characteristics 12.1 Absolute maximum ratings Rating Min Max Unit Storage Temperature -40 85 °C VDD_PA -0.3 6 V VDD_3.3V -0.3 3.6 5V tolerant GPIO Voltages -0.3 5.5 V VSS-0.3 VDD_3.3V+0.3 V Maximum output current sourced or sunk by any GPIO pad 25 mA Maximum current on all GPIO pads combined 200 mA Other Terminal Voltages Table 12: Absolute maximum ratings 12.
12.3 Input/output terminal characteristics 12.4 Digital Digital terminals Min Typ Max Unit V IL input logic level low 1.7V ≤ VDD ≤ 3.6V VSS-0.3V - 0.15VDD V V IH input logic level high 1.7V ≤ VDD ≤ 3.6V 0.8VDD - VDD+0.3V V - - 0.4 V 2.4 - VDD V Input voltage levels Output voltage levels V OL output logic level low, Vdd = 3.6 V, Iol = 7 mA V OH output logic level high Vdd = 3.6 V, Ioh = -12 mA Table 14: Digital terminal electrical characteristics Frequency Min Typ max 32.
12.6 Power consumption Consumption type Current Unit Supply domain Total maximum 400 mA both CPU average 100 mA VDD_3.3V Typical average program execution consumption CPU idle 33 mA VDD_3.3V Idle mode, instant wakeup CPU sleep 40 µA VDD_3.
Curre nt Unit Description Transmit consumption 143 mA Typical average module consumption during full rate data transfer, system does not enter deep sleep due to constant data traffic (Ethernet MAC enabled for testing) Receive consumption 127 mA Typical average module consumption during full rate data transfer, system does not enter deep sleep due to constant data traffic Access point mode 108 mA Typical average idle current when configured as an AP, does not enter deep sleep due to AP mode req
13 RF Characteristics min max 1 11 (default), 13 (ETSI) 2412 2472 Channel Frequency MHz Table 19: Supported frequencies Standard Supported bit rates 802.11b 1, 2, 5.5, 11Mbps 802.11g 6, 9, 12, 18, 24, 36, 48, 54Mbps 802.11n, HT, 20MHz, 800ns 6.5, 13, 19.5, 26, 39, 52, 58.5, 65Mbps 802.11n, HT, 20MHz, 400ns 7.2, 14.4, 21.7, 28.9, 43.3, 57.8, 65, 72.2Mbps Table 20: Supported modulations 802.11b Typ 802.11g Typ 802.11n short GI Typ 802.
Modulation type Typ 802.11b +16 dBm 802.11g +14 dBm 802.11n +14 dBm Table 22: Transmitter output power at maximum setting Modulation type Min Typ Max TX loss -2.5 -3 -3.5 dB RX gain (using internal LNA) 8 10 12 dB 2.0 2.5 dB Internal LNA noise figure Table 23: BT antenna sharing interface properties Typ Max 802.
14 Physical dimensions Figure 9: Physical dimensions Figure 10: WF121-A recommended PCB land pattern Silicon Labs Page 34 of 45
15 Layout guidelines 15.1 WF121-E RF output can be taken directly from the U.FL connector of the module, and no antenna clearances need to be made for the module. 15.2 WF121-N The RF output is taken from the ANT pin at the end of the device. In other variants this pin is not connected. The antenna trace should be properly impedance controlled and kept short. Figure 6 shows a typical trace from the RF pin to a SMA connector.
CPW Ground W = 0.15 mm G = 0.25 mm RF GROUND Prepreg, εr = 3.7 RF GROUND h = 0.076 mm RF GROUND FR4, εr = 4.6 GND stitching vias MICROSTRIP W = 1.8 mm h = 1 mm FR4, εr = 4.6 RF GROUND Figure 12: Example cross section of two different 50 ohm transmission line 15.3 WF121-A Figure 13: Example layouts, board edge placement on left, board corner on right The impedance matching of the antenna is designed for a layout similar to the module evaluation board.
ANY metal in close proximity of the antenna will prevent the antenna from radiating freely. It is recommended not to place any metal or other conductive objects closer than 20 mm to the antenna except in the directions of the ground planes of the module itself. For optimal performance, place the antenna end of the module outside any metal surfaces and objects in the application, preferably on the device corner.
• Split a ground plane ONLY if you know exactly what you are doing. Splitting the plane may cause more harm than good if applied incorrectly. The ground plane acts as a part of the antenna system. Insufficient ground planes or large separate sensitive signal ground planes will easily cause the coupled transmitted pulses to be AM-demodulated by semiconductor junctions around the board, degrading system performance.
16 Soldering recommendations WF121 is compatible with industrial standard reflow profile for Pb-free solders. The reflow profile used is dependent on the thermal mass of the entire populated PCB, heat transfer efficiency of the oven and particular type of solder paste used. Consult the datasheet of particular solder paste for profile configurations. The following recommendations apply for soldering the module to ensure reliable solder joint and operation of the module after soldering.
17 Certifications WF121 is compliant to the following specifications: 17.1 CE WF121 is in conformity with the essential requirements and other relevant requirements of the R&TTE Directive (1999/5/EC). The product is conformity with the following standards and/or normative documents. • EMC (immunity only) EN 301 489-17 V.2.2.1 in accordance with EN 301 489-1 V1.9.2 • Radiated emissions EN 300 328 V1.9.1 • Safety standards: EN 60950-1:2006 + A11:2009 + A1:2010 + A12:2011 + A2:2013 17.
having a gain greater than the maximum gain indicated for that type, are strictly prohibited for use with this device. See table 25 for the approved antennas for WF121-E and WF121-N.
17.2.1 FCC et IC Cet appareil est conforme à l’alinéa 15 des règles de la FCC. Deux conditions sont à respecter lors de son utilisation : (1) cet appareil ne doit pas créer d’interférence susceptible de causer un quelconque dommage et, (2) cet appareil doit accepter toute interférence, quelle qu’elle soit, y compris les interférences susceptibles d’entraîner un fonctionnement non requis.
appartiennent sont strictement interdites d’utilisation avec ce matériel. Veuillez vous référer au tableau 25 concernant les antennes approuvées pour les WF121.
« Inclut la certification IC 5123A-BGTWF121 » L’intégrateur du module WF121 ne doit utiliser que les antennes répertoriées dans le tableau 25 certifiées pour ce module. L’intégrateur est tenu de ne fournir aucune information à l’utilisateur final autorisant ce dernier à installer ou retirer le module RF, ou bien changer les paramètres RF du module, dans le manuel d’utilisation du produit final.
18 Qualified Antenna Types for WF121-E This device has been designed to operate with the antennas listed below, and having a maximum gain of 2.14 dB. Antennas not included in this list or having a gain greater than 2.14 dB are strictly prohibited for use with this device. The required antenna impedance is 50 ohms. Antenna Type Dipole Qualified Antenna Types for WT121-E Maximum Gain 2.
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