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Xylem H-264 User Manual

Page 14

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ASI v2 Operations (PRELIMINARY)

where N is the decimal count and V is battery voltage. The transmitter cutoff threshold is a

count of 2005, at 9.00 volts.

Put High Speed Xtal MCLK on P16 & Xtal2 on ACLK

This diagnostic is used to measure the accuracy of the precision crystal time base, and the

current consumption during high speed processing. The 6.500 MHz crystal is started, selected

as the processor clock and output on “MCLK” (P16). This is the time base used for the FSK

tone generation and high speed processing during transmission and therefore is required to be

precise. The measured frequency at room temperature should be between 6.500325 MHz and

6.499675 MHz (or +/- 50 ppm). Additionally, the 32.768 kHz crystal clock is output to test point

“ACLK” (P17, or J3 pin 2). This is used for baud rate timing, the transmitter “watch dog timer”,

the transmitter duty cycle timer and the Field Test Tool transmission timer. At room

temperature “ACLK” should measure between 32,767.34 Hz and 32,768.66 Hz (or +/- 20 ppm).

Put DCO MCLK on P16

This diagnostic is used to measure the RC DCO frequency and current during low speed

processing (“Buffer Conversion Processing’). The basic MSP430 RC DCO clock is output on

“MCLK” (P16). As described in the SWDelayS and SWDelayL diagnostic routines above, this

oscillator specification is very wide. The nominal frequency is 780 kHz (at 3.3 V), but can range

between 624 kHz and 934 kHz (+/- 20%).