38
edits
Changes
Add some instruction timings from simulator
[[File:TX circuit modified.jpg|alt=Picture of circuit board|thumb|Picture of TX circuit, highlighting components to remove to disable amplifier and a replacement jumper.]]
When testing, it's important not to transmit on unlicensed frequencies. Emissions can be eliminated by replacing the RF amplifier with a jumper between pins 1 and 3, and terminating the load at the antenna connection. The amplifier is an SOT-89 device just above the "-" terminal of B3. To access the RF chain, the shield housing may need to be temporarily removed. Also remove the bias feed resistor just below the "L104" marking. Then, remove the transmitter antenna from the "ANT1" connections. Use a 50 ohm resistor across the two terminals to provide a terminating load and eliminate any further transmission. Near-field reception is still possible after making these changes.
==Instruction Timing Tables==
These are based on the ST Visual Develop 4.3.12 Simulator. Hopefully it is accurate. I've only done the instructions needed for writing a software UART, since the hardware UART doesn't seem to be brought out on the edge-connector.
{| class="wikitable"
|+
!instruction
!cycles
!Purpose
!condition tested
|-
|sim
|2
|Set instruction mask(disable interrupts)
|
|-
|nop
|2
|no-op
|
|-
|bres
|5
|bit-reset
|;reset a GPIO pin
BRES PADR, 0
|-
|bcp
|2
|bit-compare
|BCP A,0
|-
|jreq
|3
|jump
|jump not taken
jump taken
|-
|bset
|5
|bit-set
|;set a GPIO pin
BSET PADR, 0
|-
|jrt
|3
|jump "right there"?
|
|}
==Reference==
https://www.nws.noaa.gov/directives/010/pd01014001b.pdf - Rawinsonde Operations - some more technical data on radiosonde operations.
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