A proof-of-concept of enabling PicoRV32 interrupts. Two interrupt
sources, which can be triggered by writes to memory addresses, are
added. The design has only been simulated, not run on hardware.
Synthesis:
Ice40 LC utilization is 93% (4934/5280) when built using tkey-builder:4
Simulation:
A `tb_application_fpga_irqpoc` target is added. Running `make
tb_application_fpga_irqpoc` creates `tb_application_fpga_sim.fst` which
can be inspected in GTKWave or Surfer.
Firmware:
A simple firmware is added in `fw/irqpoc`. It enables both interrupts
and triggers each interrupt once.
Custom PicoRV32 instructions are located in `custom_ops.S`. It is
imported from upstream PicoRV32 commit:
70f3c33ac8
For ages we have had a comment saying:
For Verilator 5.019 -Wno-GENUNNAMED needs to be added to LINT_FLAGS for the
cell library.
With the new tkey-builder we have 5.028, so it's time to apply this flag.
Fix CDC configuration problem on Windows when we have a composite
device (multiple different Device Classes). Add "Interface Association
Descriptor" to make it work.
Fix off-by-one UART bitrate counter value that will make the RX
sampling and TX sending drift. The impact gets higher as the baudrate
increases and the bitrate counter value gets smaller.
Reconfigure the baudrate to keep 500 kbaud.
Correct a forgotten test in testfw that wasn't updated the last time
frequency was raised in commit
75b028505f0d6dc685d37b84d73ddb9db5ee7ea2 in June 17, 2024.
- Use CTS signals to let the FPGA and CH552 signal each other that
it is OK send UART data.
- Update the CH552 rx and frame handling logic.
- Fix minor spelling errors and indentation
Add incoming and outgoing CTS (Clear To Send) signals for the FPGA to
let the CH552 and FPGA signal each other that it is OK to send UART
data. The CTS signals indicate "OK to send" if high. If an incoming
CTS signal goes low, the receiver of that signal should immediatly
stop sending UART data.
Throwing away mode and length from incoming data. Adding mode and
length to outgoing data.
Splitting responses into frames small enough for the USB<->UART
transceiver to handle.
- Add USB HID support.
- Introduce a small protocol to distinguish between CDC and HID data
sent over the UART.
- Add some debug printing.
- Cleanup of code and formatting.
- Extend hardware checks for invalid memory accesses to include
checking more address space.
- In fw include file: fix two typos for memory ranges that relates to
above that fortunately have no impact on functionality.
synth.json shouldn't depend on uds.hex and udi.hex because that
triggers a complete rebuild of the bitstream if the UDI or UDS are
changed.
Instead, we want only the application_fpga.asc to depend on them, so
we can patch in the UDS and UDI with tools/patch_uds_udi.py in an
existing application_fpga_par.json.
- Compare against an expected result and count errors
- Exit with the right error code
- Lower write_word() to 1 clk cycle instead of two. It only requires one
clock cycle to write, otherwise if it is two one have to compensate for it
in the tests since we are counting cycles.
Remove redundant timer state. This fixes a bug where the timer misses a
clock cycle every time the prescaler counter reaches 1. This means if
one uses a large prescaler, like 18E6, it is barely noticeable, but if
one have a low prescaler and a high timer value it becomes significant.
This also yields the running_* registers redundant, which are removed.
Add clarity to the readme.
Update the timer to default to values of one, for prescaler and timer
count.
This removes the possibility to configure the bit rate, data bits and
stop bits at runtime from the API. This reduces the
usage of LCs with ~4%.
It is still possible to configure the core before building.
Update digest of application_fpga.bin.sha256
