Embedded Systems Design Europe - November 2007 - (Page 17) microcontrollers input pin name for the UART Rx pin may be controlled by a coded value in the SFR. Each value of this bit combination may specify one remappable pin; a “0” value may specify the RP0 pin, a “1” may specify the RP1 pin, and so on. This register interface prevents the assignment of two different pins to one function, as the SFR control bits can only have one value at any given time. Some MCU vendors also provide the ability to prevent accidental changes to the I/O configurations. To assist in this endeavor, these configuration registers may be locked and can only be unlocked for a small duration through a special key sequence. Some vendors provide an additional level of protection to prevent accidental I/O changes during an EMC event, by creating an inverted copy of all configuration bit registers and running a constant integrity check on the hardware by comparing this copy with the original value. The EMC event will try to corrupt all bits, either toward logic high or low. Therefore, this complimentary bit checking gives solid protection. On MCUs with flexible pin mapping, peripherals don’t have default pin- outs. Hence, you must initialize pinouts before peripherals can be used. In the register-based flexible pin-mapping feature, after power up, the pin-mapping function comes out of reset with all outputs disconnected and all inputs mapped to a default register. Therefore, ACAL - Your LANTRONIX EMBEDDED ETHERNET & WIRELESS NETWORKING for demos, p ro duc t i nfo, pricing and technical suppor t find your local AC AL office at DISTRIBUTOR for SPECIALIST Serial-to-WiFi device server • Affordable embedded 802.11 b/g wireless networking • Wired Ethernet-to-wireless bridging • IEEE 802.11i-PSK,WPA-PSK, TKIP • Optional 256-bit AES end-to-end encryption Serial-to-Ethernet compact device server • 256-bit AES encryption for secure communications • Web-enable virtually any electronic device SOLUTIONS. Serial-to-Ethernet gateway module • Integrated module with RJ45 featuring dedicated networking SoC • Up to 230 Kbps data rate www.acal.co.uk G E R M A N Y • N E T H E R L A N D S • B E L G I U M • F R A N C E • I TA LY U K • S PA I N • N O R WAY • D E N M A R K • F I N L A N D • S W E D E N 015-016-017-018-019_ESDE.indd 17 6/11/07 13:35:18 http://www.acal.co.uk http://www.acal.co.uk
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