probe: split pioasm and setup code into variant files, and add OEN variant

Author: P33M

CMakeLists.txt

@@ -36,6 +36,7 @@ target_include_directories(picoprobe PRIVATE
 target_compile_options(picoprobe PRIVATE -Wall)
 
 pico_generate_pio_header(picoprobe ${CMAKE_CURRENT_LIST_DIR}/src/probe.pio)
+pico_generate_pio_header(picoprobe ${CMAKE_CURRENT_LIST_DIR}/src/probe_oen.pio)
 
 target_include_directories(picoprobe PRIVATE src)
 

README.md

@@ -3,3 +3,9 @@ Picoprobe allows a Pico / RP2040 to be used as USB -> SWD and UART bridge. This
 
 # Documentation
 Picoprobe documentation can be found in the [Pico Getting Started Guide](https://datasheets.raspberrypi.com/pico/getting-started-with-pico.pdf). See "Appendix A: Using Picoprobe".
+
+# TODO
+- TinyUSB's vendor interface is FIFO-based and not packet-based. Using raw tx/rx callbacks is preferable as this stops DAP command batches from being concatenated, which confused openOCD.
+- Instead of polling, move the DAP thread to an asynchronously started/stopped one-shot operation to reduce CPU wakeups
+- AutoBaud selection, as PIO is a capable frequency counter
+- Possibly include RTT support

src/probe.c

@@ -111,49 +111,13 @@ void probe_write_mode(void) {
  while(pio_sm_get_pc(pio0, PROBE_SM) != probe.offset + probe_offset_out_idle);
 }
 
-void probe_gpio_init()
-{
-#if defined(PROBE_PIN_RESET)
- // Target reset pin: pull up, input to emulate open drain pin
- gpio_pull_up(PROBE_PIN_RESET);
- // gpio_init will leave the pin cleared and set as input
- gpio_init(PROBE_PIN_RESET);
-#endif
- // Funcsel pins
- pio_gpio_init(pio0, PROBE_PIN_SWCLK);
- pio_gpio_init(pio0, PROBE_PIN_SWDIO);
- // Make sure SWDIO has a pullup on it. Idle state is high
- gpio_pull_up(PROBE_PIN_SWDIO);
-}
-
 void probe_init() {
  if (!probe.initted) {
  uint offset = pio_add_program(pio0, &probe_program);
  probe.offset = offset;
 
  pio_sm_config sm_config = probe_program_get_default_config(offset);
-
- // Set SWCLK as a sideset pin
- sm_config_set_sideset_pins(&sm_config, PROBE_PIN_SWCLK);
-
- // Set SWDIO offset
- sm_config_set_out_pins(&sm_config, PROBE_PIN_SWDIO, 1);
- sm_config_set_set_pins(&sm_config, PROBE_PIN_SWDIO, 1);
-#ifdef PROBE_PIN_SWDI
- sm_config_set_in_pins(&sm_config, PROBE_PIN_SWDI);
-#else
- sm_config_set_in_pins(&sm_config, PROBE_PIN_SWDIO);
-#endif
-
- // Set SWD and SWDIO pins as output to start. This will be set in the sm
- pio_sm_set_consecutive_pindirs(pio0, PROBE_SM, PROBE_PIN_OFFSET, 2, true);
-
- // shift output right, autopull off, autopull threshold
- sm_config_set_out_shift(&sm_config, true, false, 0);
- // shift input right as swd data is lsb first, autopush off
- sm_config_set_in_shift(&sm_config, true, false, 0);
-
- // Init SM with config
+ probe_sm_init(&sm_config);
  pio_sm_init(pio0, PROBE_SM, offset, &sm_config);
 
  // Set up divisor

src/probe.h

@@ -26,14 +26,21 @@
 #ifndef PROBE_H_
 #define PROBE_H_
 
+#if defined(PROBE_IO_RAW) || defined(PROBE_IO_SWDI)
+#include "probe.pio.h"
+#endif
+
+#if defined(PROBE_IO_OEN)
+#include "probe_oen.pio.h"
+#endif
+
 void probe_set_swclk_freq(uint freq_khz);
 void probe_write_bits(uint bit_count, uint32_t data_byte);
 uint32_t probe_read_bits(uint bit_count);
 
 void probe_read_mode(void);
 void probe_write_mode(void);
 
-void probe_gpio_init(void);
 void probe_init(void);
 void probe_deinit(void);
 

src/probe.pio

@@ -49,3 +49,47 @@ in_posedge_bitloop:
  jmp x-- in_posedge_bitloop side 0x0 ;
  push ; Push to rx fifo when done
  jmp in_posedge ; Jump back to start
+
+; Implement probe_gpio_init() and probe_sm_init() methods here - set pins, offsets, sidesets etc
+% c-sdk {
+
+static inline void probe_gpio_init()
+{
+#if defined(PROBE_PIN_RESET)
+ // Target reset pin: pull up, input to emulate open drain pin
+ gpio_pull_up(PROBE_PIN_RESET);
+ // gpio_init will leave the pin cleared and set as input
+ gpio_init(PROBE_PIN_RESET);
+#endif
+ // Funcsel pins
+ pio_gpio_init(pio0, PROBE_PIN_SWCLK);
+ pio_gpio_init(pio0, PROBE_PIN_SWDIO);
+ // Make sure SWDIO has a pullup on it. Idle state is high
+ gpio_pull_up(PROBE_PIN_SWDIO);
+}
+
+static inline void probe_sm_init(pio_sm_config* sm_config) {
+
+ // Set SWCLK as a sideset pin
+ sm_config_set_sideset_pins(sm_config, PROBE_PIN_SWCLK);
+
+ // Set SWDIO offset
+ sm_config_set_out_pins(sm_config, PROBE_PIN_SWDIO, 1);
+ sm_config_set_set_pins(sm_config, PROBE_PIN_SWDIO, 1);
+#ifdef PROBE_IO_SWDI
+ sm_config_set_in_pins(sm_config, PROBE_PIN_SWDI);
+#else
+ sm_config_set_in_pins(sm_config, PROBE_PIN_SWDIO);
+#endif
+
+
+ // Set SWD and SWDIO pins as output to start. This will be set in the sm
+ pio_sm_set_consecutive_pindirs(pio0, PROBE_SM, PROBE_PIN_OFFSET, 2, true);
+
+ // shift output right, autopull off, autopull threshold
+ sm_config_set_out_shift(sm_config, true, false, 0);
+ // shift input right as swd data is lsb first, autopush off
+ sm_config_set_in_shift(sm_config, true, false, 0);
+}
+
+%}

src/probe_oen.pio

@@ -0,0 +1,73 @@
+; Output-enable active-low variant of the SWD probe
+
+.program probe
+.side_set 2 opt
+
+; SWDIO_OEN is pin 0, SWCLK pin 1, SWDIO (out) pin 2, SWDI (in) pin 3.
+; Pin 0 and 1 are sideset pins
+public out_negedge:
+ set pindirs, 0x1 side 0x0 ; OE_N 0, data high, clock 0
+public out_idle:
+ pull ; pull nbits - 1
+ mov x, osr
+ pull ; pull data
+public out_negedge_bitloop:
+ out pins, 1 side 0x0
+ jmp x-- out_negedge_bitloop side 0x2 ; OE_N 0, clock high
+ set pins, 1 side 0x0 ; drive data high (idle bus state)
+ push ; Push to rx fifo just so processor knows when done
+ jmp out_negedge ; Wait for next transaction
+
+public in_posedge:
+ set pindirs, 0x0 side 0x1 ; OE_N 1, data high, clock 0
+public in_idle:
+ pull
+ mov x, osr
+in_posedge_bitloop:
+ in pins, 1 side 0x1 ; OE_N 1, clock 0
+ jmp x-- in_posedge_bitloop side 0x3 ; OE_N 1, clock 1
+ push
+ jmp in_posedge
+
+
+; Implement probe_gpio_init() and probe_sm_init() methods here - set pins, offsets, sidesets etc
+% c-sdk {
+
+void probe_gpio_init()
+{
+#if defined(PROBE_PIN_RESET)
+ // Target reset pin: pull up, input to emulate open drain pin
+ gpio_pull_up(PROBE_PIN_RESET);
+ // gpio_init will leave the pin cleared and set as input
+ gpio_init(PROBE_PIN_RESET);
+#endif
+ // Funcsel pins
+ pio_gpio_init(pio0, PROBE_PIN_SWDIOEN);
+ pio_gpio_init(pio0, PROBE_PIN_SWCLK);
+ pio_gpio_init(pio0, PROBE_PIN_SWDIO);
+
+ // Make sure SWDIO has a pullup on it. Idle state is high
+ gpio_pull_up(PROBE_PIN_SWDIO);
+ gpio_pull_up(PROBE_PIN_SWDIOEN);
+}
+
+void probe_sm_init(pio_sm_config* sm_config) {
+
+ // Set SWDIOEN and SWCLK as sideset pins
+ sm_config_set_sideset_pins(&sm_config, PROBE_PIN_SWDIOEN);
+
+ // Set SWDIO offset
+ sm_config_set_out_pins(sm_config, PROBE_PIN_SWDIO, 1);
+ sm_config_set_set_pins(sm_config, PROBE_PIN_SWDIO, 1);
+ sm_config_set_in_pins(sm_config, PROBE_PIN_SWDI);
+
+ // Set SWDIOEN, SWD and SWDIO pins as output to start. This will be set in the sm
+ pio_sm_set_consecutive_pindirs(pio0, PROBE_SM, PROBE_PIN_OFFSET, 3, true);
+
+ // shift output right, autopull off, autopull threshold
+ sm_config_set_out_shift(sm_config, true, false, 0);
+ // shift input right as swd data is lsb first, autopush off
+ sm_config_set_in_shift(sm_config, true, false, 0);
+}
+
+%}