mirror of https://github.com/Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
91 lines
3.5 KiB
91 lines
3.5 KiB
* TI - TSC ADC (Touschscreen and analog digital converter) |
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
|
|
|
Required properties: |
|
- mfd |
|
compatible: Should be |
|
"ti,am3359-tscadc" for AM335x/AM437x SoCs |
|
"ti,am654-tscadc", "ti,am3359-tscadc" for AM654 SoCs |
|
- child "tsc" |
|
compatible: Should be "ti,am3359-tsc". |
|
ti,wires: Wires refer to application modes i.e. 4/5/8 wire touchscreen |
|
support on the platform. |
|
ti,x-plate-resistance: X plate resistance |
|
ti,coordinate-readouts: The sequencer supports a total of 16 |
|
programmable steps each step is used to |
|
read a single coordinate. A single |
|
readout is enough but multiple reads can |
|
increase the quality. |
|
A value of 5 means, 5 reads for X, 5 for |
|
Y and 2 for Z (always). This utilises 12 |
|
of the 16 software steps available. The |
|
remaining 4 can be used by the ADC. |
|
ti,wire-config: Different boards could have a different order for |
|
connecting wires on touchscreen. We need to provide an |
|
8 bit number where in the 1st four bits represent the |
|
analog lines and the next 4 bits represent positive/ |
|
negative terminal on that input line. Notations to |
|
represent the input lines and terminals resoectively |
|
is as follows: |
|
AIN0 = 0, AIN1 = 1 and so on till AIN7 = 7. |
|
XP = 0, XN = 1, YP = 2, YN = 3. |
|
- child "adc" |
|
compatible: Should be |
|
"ti,am3359-adc" for AM335x/AM437x SoCs |
|
"ti,am654-adc", "ti,am3359-adc" for AM654 SoCs |
|
ti,adc-channels: List of analog inputs available for ADC. |
|
AIN0 = 0, AIN1 = 1 and so on till AIN7 = 7. |
|
|
|
Optional properties: |
|
- child "tsc" |
|
ti,charge-delay: Length of touch screen charge delay step in terms of |
|
ADC clock cycles. Charge delay value should be large |
|
in order to avoid false pen-up events. This value |
|
effects the overall sampling speed, hence need to be |
|
kept as low as possible, while avoiding false pen-up |
|
event. Start from a lower value, say 0x400, and |
|
increase value until false pen-up events are avoided. |
|
The pen-up detection happens immediately after the |
|
charge step, so this does in fact function as a |
|
hardware knob for adjusting the amount of "settling |
|
time". |
|
|
|
- child "adc" |
|
ti,chan-step-opendelay: List of open delays for each channel of |
|
ADC in the order of ti,adc-channels. The |
|
value corresponds to the number of ADC |
|
clock cycles to wait after applying the |
|
step configuration registers and before |
|
sending the start of ADC conversion. |
|
Maximum value is 0x3FFFF. |
|
ti,chan-step-sampledelay: List of sample delays for each channel |
|
of ADC in the order of ti,adc-channels. |
|
The value corresponds to the number of |
|
ADC clock cycles to sample (to hold |
|
start of conversion high). |
|
Maximum value is 0xFF. |
|
ti,chan-step-avg: Number of averages to be performed for each |
|
channel of ADC. If average is 16 then input |
|
is sampled 16 times and averaged to get more |
|
accurate value. This increases the time taken |
|
by ADC to generate a sample. Valid range is 0 |
|
average to 16 averages. Maximum value is 16. |
|
|
|
Example: |
|
tscadc: tscadc@44e0d000 { |
|
compatible = "ti,am3359-tscadc"; |
|
tsc { |
|
ti,wires = <4>; |
|
ti,x-plate-resistance = <200>; |
|
ti,coordiante-readouts = <5>; |
|
ti,wire-config = <0x00 0x11 0x22 0x33>; |
|
ti,charge-delay = <0x400>; |
|
}; |
|
|
|
adc { |
|
ti,adc-channels = <4 5 6 7>; |
|
ti,chan-step-opendelay = <0x098 0x3ffff 0x098 0x0>; |
|
ti,chan-step-sampledelay = <0xff 0x0 0xf 0x0>; |
|
ti,chan-step-avg = <16 2 4 8>; |
|
}; |
|
}
|
|
|