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Wolfgang Hottgenroth
2025-01-13 14:01:10 +01:00
parent 8c816cdb27
commit 6b18387931
1 changed files with 12 additions and 9 deletions
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content/content/articles/rgb-driver.md
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@ -1,4 +1,6 @@
## Debugging ## Generating signals for PL 9823 using a MSP430
### Debugging
``` ```
mspdebug rf2500 gdb mspdebug rf2500 gdb
@ -10,7 +12,7 @@ Attention: the gdb in the TI toolchain package is broken, use the one from Debia
## Signals Working Cycler ### Signals Working Cycler
These signals are related to code under tag `cycler_works_include_output_stage`. These signals are related to code under tag `cycler_works_include_output_stage`.
@ -26,7 +28,7 @@ Schematics and legend for signals:
![](./docs/schematics.jpeg) ![](./docs/schematics.jpeg)
### Some more explanations #### Some more explanations
Consider above schematics and the screen shot "Last octets" from the oscilloscope. Consider above schematics and the screen shot "Last octets" from the oscilloscope.
@ -58,7 +60,7 @@ Additionally, when the first bit of a full draw screen cycle is presented at P1.
## Timing ### Timing
Complete cycle: 2.48us Complete cycle: 2.48us
@ -73,7 +75,7 @@ Long pulse: 1.18us
![](./docs/pulse_long.png) ![](./docs/pulse_long.png)
## Load Time ### Load Time
During of loading data into five LEDs: 297us During of loading data into five LEDs: 297us
@ -93,7 +95,7 @@ During of loading data into six LEDs: 297us
| 200 | | 11.8ms | | 200 | | 11.8ms |
## Reset Circuitry ### Reset Circuitry
It appears that the output voltage of the power supply raises that slow, that the MCU It appears that the output voltage of the power supply raises that slow, that the MCU
will not handle the reset correctly. will not handle the reset correctly.
@ -107,22 +109,23 @@ The circuit generates the following signals:
![](./docs/reset-signal.png) ![](./docs/reset-signal.png)
#### Reference voltage (green): ##### Reference voltage (green):
```math ```math
U_ref = 3.3V \frac{22k\Omega}{22k\Omega + 10k\Omega} = 2.2V U_ref = 3.3V \frac{22k\Omega}{22k\Omega + 10k\Omega} = 2.2V
``` ```
#### Trigger voltage (purple): ##### Trigger voltage (purple):
```math ```math
U_trigg = 3.3V \frac{330k\Omega}{330k\Omega + 82k\Omega} = 2.64V U_trigg = 3.3V \frac{330k\Omega}{330k\Omega + 82k\Omega} = 2.64V
``` ```
#### RC constant: ##### RC constant:
```math ```math
\tau = 82k\Omega \cdot 100nF = 8.2ms \tau = 82k\Omega \cdot 100nF = 8.2ms
``` ```