Clarify clock terminology and speed #597
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Currently there is some ambiguity about clock terminology and speed. This attempts to differentiate between a System Clock of ~1MHz and a Master Clock of ~4MHz (2x those in Double-speed mode). Alternatively "Oscillation Clock" could be used if that's preferable to "Master Clock"
avivace
reviewed
May 8, 2025
| @@ -5,7 +5,7 @@ | |||
| Pin | Name | Explanation | |||
| ------|--------|-------------- | |||
| 1 | VDD | Power Supply +5V DC | |||
| 2 | PHI | System Clock | |||
| 2 | PHI | System Clock ≅ 1.05 MHz <br> (CGB Double-speed mode: ≅ 2.10 MHz) | |||
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I could find only one other usage of ≅for "approx equivalent to" but many more ~. Maybe this should be clarified document wise as well?
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Right - I looked for examples of shortened MHz values and duplicated from that one instance. I think it is useful to indicate that it's an approximated value vs the full one in some way.
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Oh, to answer more directly "~" seems fine to me 👍
| The reason for that is that the sensor chip sometimes handles the signals on the rising edge of the clock, but other times on the falling edge. | ||
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| :::tip NOTE | ||
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| This means that the GB Camera shouldn't be used in GBC double speed mode! | ||
| Since the PHI signal runs twice as fast in CGB Double-speed mode the values used for exposure time should be doubled. |
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Suggested change
| Since the PHI signal runs twice as fast in CGB Double-speed mode the values used for exposure time should be doubled. | |
| Since the PHI signal runs twice as fast in CGB Double-speed mode, the values used for exposure time should be doubled. |
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Looks good to me. (BTW on this I confirmed the behavior with toxa based on his open source GB Camera rom)
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Currently there is some ambiguity about clock terminology and speed. This attempts to differentiate between a System Clock / PHI of ~1MHz and a Master Clock of ~4MHz (2x those in Double-speed mode).
Alternatively "Oscillation Clock" could be used if that's preferable to "Master Clock"
Testing the water with this approach, but open to other ideas