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Diffstat (limited to 'docs/design.adoc')
| -rw-r--r-- | docs/design.adoc | 26 |
1 files changed, 14 insertions, 12 deletions
diff --git a/docs/design.adoc b/docs/design.adoc index 06cd100..9e48fd4 100644 --- a/docs/design.adoc +++ b/docs/design.adoc @@ -486,18 +486,20 @@ Detailed specifications on the TCP socket server are in ==== Operating system -TODO - -- main controller does tcp and i2c at the same time -- simple scheduler is needed -- curriculum only has FreeRTOS and Zephyr -- Zephyr is overkill -- FreeRTOS it is - -- due to RP2040 limitations, delays are used -- most SDKs I2C drivers directly call I2C message handlers from ISR -- puzzle bus driver functions can no longer be called directly from ISR handlers due to the delay -- FreeRTOS is also used in puzzle modules, though this can likely be removed in the future +Because the main controller needs to asynchronously handle state exchanges with +puzzle modules while serving a TCP socket connection, the decision to use a +task scheduler was made. Due to the requirement that most software should be +covered by the standard curriculum (<<reqs.adoc#req:curriculum-cov>>), this +choice was between FreeRTOS and Zephyr. FreeRTOS was chosen because it is the +simplest solution, and because the features Zephyr offers over FreeRTOS are +already present in the Raspberry Pi Pico SDK. + +NOTE: Due to the issues with the RP2040 that were later discovered +cite:[handover], delays are used within the puzzle bus driver's message +handling logic. This means that due to the use of the RP2040, *all puzzle +modules* are required to use a task scheduler or similar mechanism for +deferring calls to the puzzle bus driver from the I^2^C interrupt service +routine (ISR). === NeoTrellis puzzle |