UART: Difference between revisions
From WSdev Wiki
Jump to navigationJump to search
m (Register formatting.) |
(Fixes data register. Adds register addresses and access types. Splits Serial Control into Status and Control.) |
||
| Line 6: | Line 6: | ||
This allows for an effective maximum transfer speed of 960 or 3840 bytes per second, respectively. | This allows for an effective maximum transfer speed of 960 or 3840 bytes per second, respectively. | ||
The hardware also features | The hardware also features one-byte transmit and receive buffers, which allow for a slight delay in code when handling data to/from the console. | ||
== Interrupts == | == Interrupts == | ||
| Line 12: | Line 12: | ||
The UART features two interrupts: | The UART features two interrupts: | ||
* UART Send Ready - constantly active while the transmit buffer is empty (Serial | * UART Send Ready - constantly active while the transmit buffer is empty (Serial Status bit 2), | ||
* UART Receive Ready - constantly active while the receive buffer contains a byte (Serial | * UART Receive Ready - constantly active while the receive buffer contains a byte (Serial Status bit 0). | ||
== I/O ports == | == I/O ports == | ||
=== Serial Data === | {{Anchor|Serial Data}} | ||
=== Serial Data ($B1) === | |||
<pre> | <pre> | ||
| Line 24: | Line 25: | ||
dddd dddd | dddd dddd | ||
|||| |||| | |||| |||| | ||
++++-++++- Read a byte from the | ++++-++++- Read a byte from the receive buffer, or | ||
Write a byte into the | Write a byte into the transmit buffer. | ||
</pre> | </pre> | ||
=== Serial | {{Anchor|Serial Status}} | ||
=== Serial Status ($B3 read) === | |||
<pre> | <pre> | ||
7 bit 0 | 7 bit 0 | ||
---- ---- | ---- ---- | ||
eb.. .tor | |||
|| | || ||| | ||
|| | || ||+- 1 if the receive buffer contains a byte | ||
|| | || |+-- 1 on overrun (receive buffer overflow) | ||
|| | || +--- 1 if the transmit buffer is empty (can transmit another byte) | ||
|+-------- UART speed: 0 = 9600 bps, 1 = 38400 bps | |||
+--------- UART enable: 0 = off, 1 = on | |||
</pre> | |||
{{Anchor|Serial Control}} | |||
=== Serial Control ($B3 write) === | |||
<pre> | |||
7 bit 0 | |||
---- ---- | |||
ebO. .... | |||
||| | |||
||+------- Write 1 to reset overrun | ||+------- Write 1 to reset overrun | ||
|+-------- UART speed: 0 = 9600 bps, 1 = 38400 bps | |+-------- UART speed: 0 = 9600 bps, 1 = 38400 bps | ||
+--------- UART enable: 0 = off, 1 = on | +--------- UART enable: 0 = off, 1 = on | ||
</pre> | </pre> | ||
Revision as of 11:30, 22 August 2023
The WonderSwan's EXT port features an UART operating with the following configuration:
- 9,600 or 38,400 bps (bauds per second),
- 8N1 (8 data bits followed by 1 stop bit, no parity).
This allows for an effective maximum transfer speed of 960 or 3840 bytes per second, respectively.
The hardware also features one-byte transmit and receive buffers, which allow for a slight delay in code when handling data to/from the console.
Interrupts
The UART features two interrupts:
- UART Send Ready - constantly active while the transmit buffer is empty (Serial Status bit 2),
- UART Receive Ready - constantly active while the receive buffer contains a byte (Serial Status bit 0).
I/O ports
Serial Data ($B1)
7 bit 0
---- ----
dddd dddd
|||| ||||
++++-++++- Read a byte from the receive buffer, or
Write a byte into the transmit buffer.
Serial Status ($B3 read)
7 bit 0 ---- ---- eb.. .tor || ||| || ||+- 1 if the receive buffer contains a byte || |+-- 1 on overrun (receive buffer overflow) || +--- 1 if the transmit buffer is empty (can transmit another byte) |+-------- UART speed: 0 = 9600 bps, 1 = 38400 bps +--------- UART enable: 0 = off, 1 = on
Serial Control ($B3 write)
7 bit 0 ---- ---- ebO. .... ||| ||+------- Write 1 to reset overrun |+-------- UART speed: 0 = 9600 bps, 1 = 38400 bps +--------- UART enable: 0 = off, 1 = on
