alema/usbc_soldering_iron
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refined implementation

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This commit is contained in:
Alessandro Mauri 2026-04-05 17:00:53 +02:00
parent 5a6488535d
commit 03bf92f505
1 changed files with 59 additions and 82 deletions
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141
fw/programmer/src/bitbang_rvswdio_pico.h
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@ -11,13 +11,8 @@
#define PIN_SWCLK 11
// open drain emulation, the pin is set with output '0' and is switched between input or output
// depending on the wanted value, in the high state the line is pulled high by the pull-up and
// in the low state the line in forced low
#define OD_PULL(pin, value) gpio_set_dir((pin), (value) ? GPIO_IN : GPIO_OUT)
// wait time between line transitions
#define SWD_DELAY() busy_wait_us(1);
#define SWD_DELAY() busy_wait_us(2);
// microseconds between each register read/write
#define STOP_WAIT 8
@ -25,16 +20,17 @@
// Single wire debug (SWDIO and SWCLK)
static inline void ConfigureIOForRVSWD(void)
{
// SWDIO, open drain (emulated) with pull-up
// SWCLK forced, starts at 1
gpio_init(PIN_SWCLK);
gpio_set_pulls(PIN_SWCLK, false, false);
gpio_put(PIN_SWCLK, 1);
gpio_set_dir(PIN_SWCLK, GPIO_OUT);
// SWDIO, open drain (emulated) with pull-up
gpio_init(PIN_SWDIO);
gpio_set_pulls(PIN_SWDIO, true, false);
gpio_put(PIN_SWDIO, 0);
gpio_put(PIN_SWDIO, 1);
gpio_set_dir(PIN_SWDIO, GPIO_IN);
gpio_init(PIN_SWCLK);
gpio_set_pulls(PIN_SWCLK, false, false);
gpio_put(PIN_SWCLK, 0);
gpio_set_dir(PIN_SWCLK, GPIO_OUT);
}
@ -45,38 +41,12 @@ static inline void ConfigureIOForRVSWIO(void)
}
static inline void rvswd_start(void)
{
// Start with both lines high
gpio_put(PIN_SWCLK, 1);
OD_PULL(PIN_SWDIO, 1);
//SWD_DELAY();
// Pull data low
OD_PULL(PIN_SWDIO, 0);
SWD_DELAY();
}
static inline void rvswd_stop(void)
{
gpio_put(PIN_SWCLK, 0);
SWD_DELAY();
OD_PULL(PIN_SWDIO, 0);
SWD_DELAY();
gpio_put(PIN_SWCLK, 1);
SWD_DELAY();
OD_PULL(PIN_SWDIO, 1);
}
void rvswd_write_bit(bool value)
{
gpio_put(PIN_SWCLK, 0);
OD_PULL(PIN_SWDIO, value);
gpio_put(PIN_SWDIO, value);
gpio_set_dir(PIN_SWDIO, GPIO_OUT);
gpio_set_dir(PIN_SWDIO, GPIO_IN);
SWD_DELAY();
gpio_put(PIN_SWCLK, 1); // Data is sampled on rising edge of clock
SWD_DELAY();
@ -85,18 +55,31 @@ void rvswd_write_bit(bool value)
bool rvswd_read_bit(void)
{
OD_PULL(PIN_SWDIO, 0);
gpio_put(PIN_SWDIO, 1);
gpio_set_dir(PIN_SWDIO, GPIO_IN);
gpio_put(PIN_SWCLK, 0);
OD_PULL(PIN_SWDIO, 1);
SWD_DELAY();
bool bit = gpio_get(PIN_SWDIO);
gpio_put(PIN_SWCLK, 1); // Data is output on rising edge of clock
SWD_DELAY();
return bit;
}
static inline void rvswd_stop(void)
{
gpio_put(PIN_SWCLK, 0);
SWD_DELAY();
gpio_put(PIN_SWDIO, 0);
gpio_set_dir(PIN_SWDIO, GPIO_OUT);
SWD_DELAY();
gpio_put(PIN_SWCLK, 1);
SWD_DELAY();
gpio_put(PIN_SWDIO, 1);
gpio_set_dir(PIN_SWDIO, GPIO_IN);
}
static void MCFWriteReg32( struct SWIOState * state, uint8_t command, uint32_t value )
{
// only supported mode is SWD
@ -106,35 +89,34 @@ static void MCFWriteReg32( struct SWIOState * state, uint8_t command, uint32_t v
}
noInterrupts();
rvswd_start();
// start transaction
gpio_put(PIN_SWDIO, 0);
gpio_set_dir(PIN_SWDIO, GPIO_OUT);
SWD_DELAY();
// ADDR HOST
bool parity = false; // This time it's odd parity?
for (uint8_t position = 0; position < 7; position++) {
bool bit = (command >> (6 - position)) & 1;
bool parity = true;
for (uint32_t mask = 1<<6; mask; mask >>= 1) {
bool bit = !!(command & mask);
parity ^= bit;
rvswd_write_bit(bit);
if (bit) parity = !parity;
}
// Operation: write
rvswd_write_bit(1);
parity = !parity;
// Parity bit (even)
rvswd_write_bit(1); // Operation: write
rvswd_write_bit(parity);
rvswd_read_bit(); // ???
rvswd_read_bit(); // Seems only need to be set for first transaction (We are ignoring that though)
rvswd_read_bit(); // ???
rvswd_write_bit(0); // 0 for register, 1 for value.
rvswd_write_bit(0); // ??? Seems to have something to do with halting.
// Data
// DATA
parity = false; // This time it's even parity?
for (uint8_t position = 0; position < 32; position++) {
bool bit = (value >> (31 - position)) & 1;
for (uint32_t mask = 1<<31; mask; mask >>= 1) {
bool bit = !!(value & mask);
parity ^= bit;
rvswd_write_bit(bit);
if (bit) parity = !parity;
}
// Parity bit
@ -160,60 +142,55 @@ static int MCFReadReg32( struct SWIOState * state, uint8_t command, uint32_t * v
return -1;
}
bool parity;
noInterrupts();
rvswd_start();
// start transaction
gpio_put(PIN_SWDIO, 0);
gpio_set_dir(PIN_SWDIO, GPIO_OUT);
SWD_DELAY();
// ADDR HOST
parity = false;
for (uint8_t position = 0; position < 7; position++) {
bool bit = (command >> (6 - position)) & 1;
bool parity = false;
for (uint8_t mask = 1<<6; mask; mask >>= 1) {
bool bit = !!(command & mask);
parity ^= bit;
rvswd_write_bit(bit);
if (bit) parity = !parity;
}
// Operation: read
rvswd_write_bit(0);
// Parity bit (even)
rvswd_write_bit(0); // Operation: read
rvswd_write_bit(parity);
rvswd_read_bit(); // ??
rvswd_read_bit(); // ??
rvswd_read_bit(); // ??
rvswd_write_bit(0); // 0 for register, 1 for value
rvswd_write_bit(0); // ??? Seems to have something to do with halting?
// DATA
*value = 0;
// Data
parity = false;
uint32_t rval = 0;
for (uint8_t position = 0; position < 32; position++) {
bool bit = rvswd_read_bit();
rval <<= 1;
if (bit) {
rval |= 1;
parity ^= 1;
}
rval |= bit;
parity ^= bit;
}
*value = rval;
// Parity bit
bool parity_read = rvswd_read_bit();
if (parity_read != parity) goto read_end;
rvswd_read_bit(); // ??
rvswd_read_bit(); // ??
rvswd_read_bit(); // ??
rvswd_write_bit(1); // 1 for data
rvswd_write_bit(1); // 0 for register, 1 for value
rvswd_write_bit(0); // ??? Seems to have something to do with halting?
rvswd_stop();
interrupts();
read_end:
interrupts();
sleep_us(STOP_WAIT);
return (parity == parity_read) ? 0 : -1;
}