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General Description |
A7128 is a high data rate and low cost Sub 1GHz ISM band wireless FSK/GFSK transceiver. It integrates high sensitivity receiver (-88dBm @2Mbps / - 96 dBm @ 500Kbps @ 915MHz), high efficiency power amplifier (up to 10 dBm), frantional-N frequency synthesizer and baseband modem. In typical system, A7128 is used together with MCU (microcontroller) with very few external passive components. A7128 supports both FIFO mode and direct mode. In direct mode, A7128 supports recovery clock (CKO pin) to MCU for data latching. For packet handling, A7128 has built-in separated 64-bytes TX/RX FIFO (could be extended to 256 bytes) for data buffering and burst transmission, Auto-ack and Auto-resend scheme (max 15 cycles), dynamic FIFO length, CRC error detection, FEC error correction (1-bit data correction per code word), digital RSSI for clear channel assessment, data whitening for payload encryption / decryption, thermal sensor to monitor relative temperature, one channel 8-bits ADC for RSSI and external analog voltage conversion. Those functions are very easy to use while developing a wireless system. All features are integrated in a small QFN 4X4 20 pins package. Additional device features such as CRC filtering, Manchester encoding, carrier detect, preamble detect, frame sync of FIFO mode, AIF (Auto IF), AFC (Auto Frequency compensation), Auto calibration (VCO, IF Filter, RSSI), prgrammalbe IF Filter, multi Xtal sources, Xtal sharing are used to simplify system development and cost. A7128 supports programmable data rate is up to 2Mbps (100Kbps ~ 2Mbps) via 3-wire or 4-wire SPI.For power saving, A7128 supports deep sleep mode (no register retention), sleep mode (with register retention), idle mode, standby mode. For easy-to-use, A7128 has a unique SPI command set called Strobe command that are used to control A7128’s state machine. Based on Strobe commands (via SPI), from power saving, TX delivery, RX receiving, channel monitoring, frequency hopping to auto calibrations, MCU only needs to read/write A7128’s control registers and then issue Strobe commands for everything. For MCU feedback signal, A7128 has two general purpose I/O pins (GIO1 and GIO2) to inform MCU its status so that MCU could either use polling or interrupt scheme to do radio control. Interface between MCU and A7128 is digital, it leads a simple way to develop a wireless system as well as transmission status. |