diff --git a/py/argcheck.c b/py/argcheck.c
index aea71d0bd8..bfaa5764f5 100644
--- a/py/argcheck.c
+++ b/py/argcheck.c
@@ -34,12 +34,12 @@ void mp_arg_check_num(uint n_args, uint n_kw, uint n_args_min, uint n_args_max,
     }
 }
 
-void mp_arg_parse_all(uint n_pos, const mp_obj_t *pos, mp_map_t *kws, uint n_allowed, const mp_arg_parse_t *allowed, mp_arg_parse_val_t *out_vals) {
+void mp_arg_parse_all(uint n_pos, const mp_obj_t *pos, mp_map_t *kws, uint n_allowed, const mp_arg_t *allowed, mp_arg_val_t *out_vals) {
     uint pos_found = 0, kws_found = 0;
     for (uint i = 0; i < n_allowed; i++) {
         mp_obj_t given_arg;
         if (i < n_pos) {
-            if (allowed[i].flags & MP_ARG_PARSE_KW_ONLY) {
+            if (allowed[i].flags & MP_ARG_KW_ONLY) {
                 goto extra_positional;
             }
             pos_found++;
@@ -47,7 +47,7 @@ void mp_arg_parse_all(uint n_pos, const mp_obj_t *pos, mp_map_t *kws, uint n_all
         } else {
             mp_map_elem_t *kw = mp_map_lookup(kws, MP_OBJ_NEW_QSTR(allowed[i].qstr), MP_MAP_LOOKUP);
             if (kw == NULL) {
-                if (allowed[i].flags & MP_ARG_PARSE_REQUIRED) {
+                if (allowed[i].flags & MP_ARG_REQUIRED) {
                     nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "'%s' argument required", qstr_str(allowed[i].qstr)));
                 }
                 out_vals[i] = allowed[i].defval;
@@ -57,11 +57,11 @@ void mp_arg_parse_all(uint n_pos, const mp_obj_t *pos, mp_map_t *kws, uint n_all
                 given_arg = kw->value;
             }
         }
-        if ((allowed[i].flags & MP_ARG_PARSE_KIND_MASK) == MP_ARG_PARSE_BOOL) {
+        if ((allowed[i].flags & MP_ARG_KIND_MASK) == MP_ARG_BOOL) {
             out_vals[i].u_bool = mp_obj_is_true(given_arg);
-        } else if ((allowed[i].flags & MP_ARG_PARSE_KIND_MASK) == MP_ARG_PARSE_INT) {
+        } else if ((allowed[i].flags & MP_ARG_KIND_MASK) == MP_ARG_INT) {
             out_vals[i].u_int = mp_obj_get_int(given_arg);
-        } else if ((allowed[i].flags & MP_ARG_PARSE_KIND_MASK) == MP_ARG_PARSE_OBJ) {
+        } else if ((allowed[i].flags & MP_ARG_KIND_MASK) == MP_ARG_OBJ) {
             out_vals[i].u_obj = given_arg;
         } else {
             assert(0);
diff --git a/py/runtime.h b/py/runtime.h
index 5ce4bbc5e1..0ec12082a6 100644
--- a/py/runtime.h
+++ b/py/runtime.h
@@ -5,31 +5,31 @@ typedef enum {
 } mp_vm_return_kind_t;
 
 typedef enum {
-    MP_ARG_PARSE_BOOL      = 0x001,
-    MP_ARG_PARSE_INT       = 0x002,
-    MP_ARG_PARSE_OBJ       = 0x003,
-    MP_ARG_PARSE_KIND_MASK = 0x0ff,
-    MP_ARG_PARSE_REQUIRED  = 0x100,
-    MP_ARG_PARSE_KW_ONLY   = 0x200,
-} mp_arg_parse_flag_t;
-
-typedef union _mp_arg_parse_val_t {
+    MP_ARG_BOOL      = 0x001,
+    MP_ARG_INT       = 0x002,
+    MP_ARG_OBJ       = 0x003,
+    MP_ARG_KIND_MASK = 0x0ff,
+    MP_ARG_REQUIRED  = 0x100,
+    MP_ARG_KW_ONLY   = 0x200,
+} mp_arg_flag_t;
+
+typedef union _mp_arg_val_t {
     bool u_bool;
     machine_int_t u_int;
     mp_obj_t u_obj;
-} mp_arg_parse_val_t;
+} mp_arg_val_t;
 
-typedef struct _mp_arg_parse_t {
+typedef struct _mp_arg_t {
     qstr qstr;
     machine_uint_t flags;
-    mp_arg_parse_val_t defval;
-} mp_arg_parse_t;
+    mp_arg_val_t defval;
+} mp_arg_t;
 
 void mp_init(void);
 void mp_deinit(void);
 
 void mp_arg_check_num(uint n_args, uint n_kw, uint n_args_min, uint n_args_max, bool takes_kw);
-void mp_arg_parse_all(uint n_pos, const mp_obj_t *pos, mp_map_t *kws, uint n_allowed, const mp_arg_parse_t *allowed, mp_arg_parse_val_t *out_vals);
+void mp_arg_parse_all(uint n_pos, const mp_obj_t *pos, mp_map_t *kws, uint n_allowed, const mp_arg_t *allowed, mp_arg_val_t *out_vals);
 
 mp_obj_dict_t *mp_locals_get(void);
 void mp_locals_set(mp_obj_dict_t *d);
diff --git a/stmhal/dac.c b/stmhal/dac.c
index b9f825c05e..73f1fb2593 100644
--- a/stmhal/dac.c
+++ b/stmhal/dac.c
@@ -162,19 +162,19 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_2(pyb_dac_write_obj, pyb_dac_write);
 // TODO add callback argument, to call when transfer is finished
 // TODO add double buffer argument
 
-STATIC const mp_arg_parse_t pyb_dac_write_timed_accepted_args[] = {
-    { MP_QSTR_data, MP_ARG_PARSE_REQUIRED | MP_ARG_PARSE_OBJ, {.u_obj = MP_OBJ_NULL} },
-    { MP_QSTR_freq, MP_ARG_PARSE_REQUIRED | MP_ARG_PARSE_INT, {.u_int = 0} },
-    { MP_QSTR_mode, MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT, {.u_int = DMA_NORMAL} },
+STATIC const mp_arg_t pyb_dac_write_timed_args[] = {
+    { MP_QSTR_data, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+    { MP_QSTR_freq, MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 0} },
+    { MP_QSTR_mode, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = DMA_NORMAL} },
 };
-#define PYB_DAC_WRITE_TIMED_NUM_ARGS ARRAY_SIZE(pyb_dac_write_timed_accepted_args)
+#define PYB_DAC_WRITE_TIMED_NUM_ARGS ARRAY_SIZE(pyb_dac_write_timed_args)
 
 mp_obj_t pyb_dac_write_timed(uint n_args, const mp_obj_t *args, mp_map_t *kw_args) {
     pyb_dac_obj_t *self = args[0];
 
     // parse args
-    mp_arg_parse_val_t vals[PYB_DAC_WRITE_TIMED_NUM_ARGS];
-    mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_DAC_WRITE_TIMED_NUM_ARGS, pyb_dac_write_timed_accepted_args, vals);
+    mp_arg_val_t vals[PYB_DAC_WRITE_TIMED_NUM_ARGS];
+    mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_DAC_WRITE_TIMED_NUM_ARGS, pyb_dac_write_timed_args, vals);
 
     // get the data to write
     mp_buffer_info_t bufinfo;
diff --git a/stmhal/extint.c b/stmhal/extint.c
index 2c576648b4..289a519762 100644
--- a/stmhal/extint.c
+++ b/stmhal/extint.c
@@ -239,13 +239,13 @@ STATIC mp_obj_t extint_regs(void) {
 
 // line_obj = pyb.ExtInt(pin, mode, pull, callback)
 
-STATIC const mp_arg_parse_t pyb_extint_make_new_accepted_args[] = {
-    { MP_QSTR_pin,      MP_ARG_PARSE_REQUIRED | MP_ARG_PARSE_OBJ, {.u_obj = MP_OBJ_NULL} },
-    { MP_QSTR_mode,     MP_ARG_PARSE_REQUIRED | MP_ARG_PARSE_INT, {.u_int = 0} },
-    { MP_QSTR_pull,     MP_ARG_PARSE_REQUIRED | MP_ARG_PARSE_INT, {.u_int = 0} },
-    { MP_QSTR_callback, MP_ARG_PARSE_REQUIRED | MP_ARG_PARSE_OBJ, {.u_obj = MP_OBJ_NULL} },
+STATIC const mp_arg_t pyb_extint_make_new_args[] = {
+    { MP_QSTR_pin,      MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+    { MP_QSTR_mode,     MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 0} },
+    { MP_QSTR_pull,     MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 0} },
+    { MP_QSTR_callback, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
 };
-#define PYB_EXTINT_MAKE_NEW_NUM_ARGS ARRAY_SIZE(pyb_extint_make_new_accepted_args)
+#define PYB_EXTINT_MAKE_NEW_NUM_ARGS ARRAY_SIZE(pyb_extint_make_new_args)
 
 STATIC mp_obj_t extint_make_new(mp_obj_t type_in, uint n_args, uint n_kw, const mp_obj_t *args) {
     // type_in == extint_obj_type
@@ -253,8 +253,8 @@ STATIC mp_obj_t extint_make_new(mp_obj_t type_in, uint n_args, uint n_kw, const
     // parse args
     mp_map_t kw_args;
     mp_map_init_fixed_table(&kw_args, n_kw, args + n_args);
-    mp_arg_parse_val_t vals[PYB_EXTINT_MAKE_NEW_NUM_ARGS];
-    mp_arg_parse_all(n_args, args, &kw_args, PYB_EXTINT_MAKE_NEW_NUM_ARGS, pyb_extint_make_new_accepted_args, vals);
+    mp_arg_val_t vals[PYB_EXTINT_MAKE_NEW_NUM_ARGS];
+    mp_arg_parse_all(n_args, args, &kw_args, PYB_EXTINT_MAKE_NEW_NUM_ARGS, pyb_extint_make_new_args, vals);
 
     extint_obj_t *self = m_new_obj(extint_obj_t);
     self->base.type = type_in;
diff --git a/stmhal/i2c.c b/stmhal/i2c.c
index 4b44a1a313..2c804a23d0 100644
--- a/stmhal/i2c.c
+++ b/stmhal/i2c.c
@@ -176,18 +176,18 @@ STATIC void pyb_i2c_print(void (*print)(void *env, const char *fmt, ...), void *
     }
 }
 
-STATIC const mp_arg_parse_t pyb_i2c_init_accepted_args[] = {
-    { MP_QSTR_mode,     MP_ARG_PARSE_REQUIRED | MP_ARG_PARSE_INT, {.u_int = 0} },
-    { MP_QSTR_addr,     MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT, {.u_int = 0x12} },
-    { MP_QSTR_baudrate, MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT, {.u_int = 400000} },
-    { MP_QSTR_gencall,  MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_BOOL, {.u_bool = false} },
+STATIC const mp_arg_t pyb_i2c_init_args[] = {
+    { MP_QSTR_mode,     MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 0} },
+    { MP_QSTR_addr,     MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0x12} },
+    { MP_QSTR_baudrate, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 400000} },
+    { MP_QSTR_gencall,  MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
 };
-#define PYB_I2C_INIT_NUM_ARGS ARRAY_SIZE(pyb_i2c_init_accepted_args)
+#define PYB_I2C_INIT_NUM_ARGS ARRAY_SIZE(pyb_i2c_init_args)
 
 STATIC mp_obj_t pyb_i2c_init_helper(const pyb_i2c_obj_t *self, uint n_args, const mp_obj_t *args, mp_map_t *kw_args) {
     // parse args
-    mp_arg_parse_val_t vals[PYB_I2C_INIT_NUM_ARGS];
-    mp_arg_parse_all(n_args, args, kw_args, PYB_I2C_INIT_NUM_ARGS, pyb_i2c_init_accepted_args, vals);
+    mp_arg_val_t vals[PYB_I2C_INIT_NUM_ARGS];
+    mp_arg_parse_all(n_args, args, kw_args, PYB_I2C_INIT_NUM_ARGS, pyb_i2c_init_args, vals);
 
     // set the I2C configuration values
     I2C_InitTypeDef *init = &self->i2c->Init;
@@ -295,19 +295,19 @@ STATIC mp_obj_t pyb_i2c_scan(mp_obj_t self_in) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_i2c_scan_obj, pyb_i2c_scan);
 
-STATIC const mp_arg_parse_t pyb_i2c_send_accepted_args[] = {
-    { MP_QSTR_send,    MP_ARG_PARSE_REQUIRED | MP_ARG_PARSE_OBJ, {.u_obj = MP_OBJ_NULL} },
-    { MP_QSTR_addr,    MP_ARG_PARSE_INT, {.u_int = PYB_I2C_MASTER_ADDRESS} },
-    { MP_QSTR_timeout, MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT, {.u_int = 5000} },
+STATIC const mp_arg_t pyb_i2c_send_args[] = {
+    { MP_QSTR_send,    MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+    { MP_QSTR_addr,    MP_ARG_INT, {.u_int = PYB_I2C_MASTER_ADDRESS} },
+    { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 5000} },
 };
-#define PYB_I2C_SEND_NUM_ARGS ARRAY_SIZE(pyb_i2c_send_accepted_args)
+#define PYB_I2C_SEND_NUM_ARGS ARRAY_SIZE(pyb_i2c_send_args)
 
 STATIC mp_obj_t pyb_i2c_send(uint n_args, const mp_obj_t *args, mp_map_t *kw_args) {
     pyb_i2c_obj_t *self = args[0];
 
     // parse args
-    mp_arg_parse_val_t vals[PYB_I2C_SEND_NUM_ARGS];
-    mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_I2C_SEND_NUM_ARGS, pyb_i2c_send_accepted_args, vals);
+    mp_arg_val_t vals[PYB_I2C_SEND_NUM_ARGS];
+    mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_I2C_SEND_NUM_ARGS, pyb_i2c_send_args, vals);
 
     // get the buffer to send from
     mp_buffer_info_t bufinfo;
@@ -335,19 +335,19 @@ STATIC mp_obj_t pyb_i2c_send(uint n_args, const mp_obj_t *args, mp_map_t *kw_arg
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_i2c_send_obj, 1, pyb_i2c_send);
 
-STATIC const mp_arg_parse_t pyb_i2c_recv_accepted_args[] = {
-    { MP_QSTR_recv,    MP_ARG_PARSE_REQUIRED | MP_ARG_PARSE_OBJ, {.u_obj = MP_OBJ_NULL} },
-    { MP_QSTR_addr,    MP_ARG_PARSE_INT, {.u_int = PYB_I2C_MASTER_ADDRESS} },
-    { MP_QSTR_timeout, MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT, {.u_int = 5000} },
+STATIC const mp_arg_t pyb_i2c_recv_args[] = {
+    { MP_QSTR_recv,    MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+    { MP_QSTR_addr,    MP_ARG_INT, {.u_int = PYB_I2C_MASTER_ADDRESS} },
+    { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 5000} },
 };
-#define PYB_I2C_RECV_NUM_ARGS ARRAY_SIZE(pyb_i2c_recv_accepted_args)
+#define PYB_I2C_RECV_NUM_ARGS ARRAY_SIZE(pyb_i2c_recv_args)
 
 STATIC mp_obj_t pyb_i2c_recv(uint n_args, const mp_obj_t *args, mp_map_t *kw_args) {
     pyb_i2c_obj_t *self = args[0];
 
     // parse args
-    mp_arg_parse_val_t vals[PYB_I2C_RECV_NUM_ARGS];
-    mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_I2C_RECV_NUM_ARGS, pyb_i2c_recv_accepted_args, vals);
+    mp_arg_val_t vals[PYB_I2C_RECV_NUM_ARGS];
+    mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_I2C_RECV_NUM_ARGS, pyb_i2c_recv_args, vals);
 
     // get the buffer to receive into
     mp_buffer_info_t bufinfo;
@@ -379,13 +379,13 @@ STATIC mp_obj_t pyb_i2c_recv(uint n_args, const mp_obj_t *args, mp_map_t *kw_arg
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_i2c_recv_obj, 1, pyb_i2c_recv);
 
-STATIC const mp_arg_parse_t pyb_i2c_mem_read_accepted_args[] = {
-    { MP_QSTR_data,    MP_ARG_PARSE_REQUIRED | MP_ARG_PARSE_OBJ, {.u_obj = MP_OBJ_NULL} },
-    { MP_QSTR_addr,    MP_ARG_PARSE_REQUIRED | MP_ARG_PARSE_INT, {.u_int = 0} },
-    { MP_QSTR_memaddr, MP_ARG_PARSE_REQUIRED | MP_ARG_PARSE_INT, {.u_int = 0} },
-    { MP_QSTR_timeout, MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT, {.u_int = 5000} },
+STATIC const mp_arg_t pyb_i2c_mem_read_args[] = {
+    { MP_QSTR_data,    MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+    { MP_QSTR_addr,    MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 0} },
+    { MP_QSTR_memaddr, MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 0} },
+    { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 5000} },
 };
-#define PYB_I2C_MEM_READ_NUM_ARGS ARRAY_SIZE(pyb_i2c_mem_read_accepted_args)
+#define PYB_I2C_MEM_READ_NUM_ARGS ARRAY_SIZE(pyb_i2c_mem_read_args)
 
 STATIC mp_obj_t pyb_i2c_mem_read(uint n_args, const mp_obj_t *args, mp_map_t *kw_args) {
     pyb_i2c_obj_t *self = args[0];
@@ -395,8 +395,8 @@ STATIC mp_obj_t pyb_i2c_mem_read(uint n_args, const mp_obj_t *args, mp_map_t *kw
     }
 
     // parse args
-    mp_arg_parse_val_t vals[PYB_I2C_MEM_READ_NUM_ARGS];
-    mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_I2C_MEM_READ_NUM_ARGS, pyb_i2c_mem_read_accepted_args, vals);
+    mp_arg_val_t vals[PYB_I2C_MEM_READ_NUM_ARGS];
+    mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_I2C_MEM_READ_NUM_ARGS, pyb_i2c_mem_read_args, vals);
 
     // get the buffer to read into
     mp_buffer_info_t bufinfo;
@@ -430,8 +430,8 @@ STATIC mp_obj_t pyb_i2c_mem_write(uint n_args, const mp_obj_t *args, mp_map_t *k
     }
 
     // parse args (same as mem_read)
-    mp_arg_parse_val_t vals[PYB_I2C_MEM_READ_NUM_ARGS];
-    mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_I2C_MEM_READ_NUM_ARGS, pyb_i2c_mem_read_accepted_args, vals);
+    mp_arg_val_t vals[PYB_I2C_MEM_READ_NUM_ARGS];
+    mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_I2C_MEM_READ_NUM_ARGS, pyb_i2c_mem_read_args, vals);
 
     // get the buffer to write from
     mp_buffer_info_t bufinfo;
diff --git a/stmhal/spi.c b/stmhal/spi.c
index 7e2e4ad4cf..bad71e87b1 100644
--- a/stmhal/spi.c
+++ b/stmhal/spi.c
@@ -194,24 +194,24 @@ STATIC void pyb_spi_print(void (*print)(void *env, const char *fmt, ...), void *
     }
 }
 
-STATIC const mp_arg_parse_t pyb_spi_init_accepted_args[] = {
-    { MP_QSTR_mode,     MP_ARG_PARSE_REQUIRED | MP_ARG_PARSE_INT, {.u_int = 0} },
-    { MP_QSTR_baudrate, MP_ARG_PARSE_INT, {.u_int = 328125} },
-    { MP_QSTR_polarity, MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT,  {.u_int = 1} },
-    { MP_QSTR_phase,    MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT,  {.u_int = 1} },
-    { MP_QSTR_dir,      MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT,  {.u_int = SPI_DIRECTION_2LINES} },
-    { MP_QSTR_bits,     MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT,  {.u_int = 8} },
-    { MP_QSTR_nss,      MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT,  {.u_int = SPI_NSS_SOFT} },
-    { MP_QSTR_firstbit, MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT,  {.u_int = SPI_FIRSTBIT_MSB} },
-    { MP_QSTR_ti,       MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_BOOL, {.u_bool = false} },
-    { MP_QSTR_crc,      MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_OBJ,  {.u_obj = mp_const_none} },
+STATIC const mp_arg_t pyb_spi_init_args[] = {
+    { MP_QSTR_mode,     MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 0} },
+    { MP_QSTR_baudrate, MP_ARG_INT, {.u_int = 328125} },
+    { MP_QSTR_polarity, MP_ARG_KW_ONLY | MP_ARG_INT,  {.u_int = 1} },
+    { MP_QSTR_phase,    MP_ARG_KW_ONLY | MP_ARG_INT,  {.u_int = 1} },
+    { MP_QSTR_dir,      MP_ARG_KW_ONLY | MP_ARG_INT,  {.u_int = SPI_DIRECTION_2LINES} },
+    { MP_QSTR_bits,     MP_ARG_KW_ONLY | MP_ARG_INT,  {.u_int = 8} },
+    { MP_QSTR_nss,      MP_ARG_KW_ONLY | MP_ARG_INT,  {.u_int = SPI_NSS_SOFT} },
+    { MP_QSTR_firstbit, MP_ARG_KW_ONLY | MP_ARG_INT,  {.u_int = SPI_FIRSTBIT_MSB} },
+    { MP_QSTR_ti,       MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
+    { MP_QSTR_crc,      MP_ARG_KW_ONLY | MP_ARG_OBJ,  {.u_obj = mp_const_none} },
 };
-#define PYB_SPI_INIT_NUM_ARGS ARRAY_SIZE(pyb_spi_init_accepted_args)
+#define PYB_SPI_INIT_NUM_ARGS ARRAY_SIZE(pyb_spi_init_args)
 
 STATIC mp_obj_t pyb_spi_init_helper(const pyb_spi_obj_t *self, uint n_args, const mp_obj_t *args, mp_map_t *kw_args) {
     // parse args
-    mp_arg_parse_val_t vals[PYB_SPI_INIT_NUM_ARGS];
-    mp_arg_parse_all(n_args, args, kw_args, PYB_SPI_INIT_NUM_ARGS, pyb_spi_init_accepted_args, vals);
+    mp_arg_val_t vals[PYB_SPI_INIT_NUM_ARGS];
+    mp_arg_parse_all(n_args, args, kw_args, PYB_SPI_INIT_NUM_ARGS, pyb_spi_init_args, vals);
 
     // set the SPI configuration values
     SPI_InitTypeDef *init = &self->spi->Init;
@@ -295,11 +295,11 @@ STATIC mp_obj_t pyb_spi_deinit(mp_obj_t self_in) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_spi_deinit_obj, pyb_spi_deinit);
 
-STATIC const mp_arg_parse_t pyb_spi_send_accepted_args[] = {
-    { MP_QSTR_send,    MP_ARG_PARSE_REQUIRED | MP_ARG_PARSE_OBJ, {.u_obj = MP_OBJ_NULL} },
-    { MP_QSTR_timeout, MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT, {.u_int = 5000} },
+STATIC const mp_arg_t pyb_spi_send_args[] = {
+    { MP_QSTR_send,    MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+    { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 5000} },
 };
-#define PYB_SPI_SEND_NUM_ARGS ARRAY_SIZE(pyb_spi_send_accepted_args)
+#define PYB_SPI_SEND_NUM_ARGS ARRAY_SIZE(pyb_spi_send_args)
 
 STATIC mp_obj_t pyb_spi_send(uint n_args, const mp_obj_t *args, mp_map_t *kw_args) {
     // TODO assumes transmission size is 8-bits wide
@@ -307,8 +307,8 @@ STATIC mp_obj_t pyb_spi_send(uint n_args, const mp_obj_t *args, mp_map_t *kw_arg
     pyb_spi_obj_t *self = args[0];
 
     // parse args
-    mp_arg_parse_val_t vals[PYB_SPI_SEND_NUM_ARGS];
-    mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_SPI_SEND_NUM_ARGS, pyb_spi_send_accepted_args, vals);
+    mp_arg_val_t vals[PYB_SPI_SEND_NUM_ARGS];
+    mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_SPI_SEND_NUM_ARGS, pyb_spi_send_args, vals);
 
     // get the buffer to send from
     mp_buffer_info_t bufinfo;
@@ -327,11 +327,11 @@ STATIC mp_obj_t pyb_spi_send(uint n_args, const mp_obj_t *args, mp_map_t *kw_arg
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_spi_send_obj, 1, pyb_spi_send);
 
-STATIC const mp_arg_parse_t pyb_spi_recv_accepted_args[] = {
-    { MP_QSTR_recv,    MP_ARG_PARSE_REQUIRED | MP_ARG_PARSE_OBJ, {.u_obj = MP_OBJ_NULL} },
-    { MP_QSTR_timeout, MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT, {.u_int = 5000} },
+STATIC const mp_arg_t pyb_spi_recv_args[] = {
+    { MP_QSTR_recv,    MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+    { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 5000} },
 };
-#define PYB_SPI_RECV_NUM_ARGS ARRAY_SIZE(pyb_spi_recv_accepted_args)
+#define PYB_SPI_RECV_NUM_ARGS ARRAY_SIZE(pyb_spi_recv_args)
 
 STATIC mp_obj_t pyb_spi_recv(uint n_args, const mp_obj_t *args, mp_map_t *kw_args) {
     // TODO assumes transmission size is 8-bits wide
@@ -339,8 +339,8 @@ STATIC mp_obj_t pyb_spi_recv(uint n_args, const mp_obj_t *args, mp_map_t *kw_arg
     pyb_spi_obj_t *self = args[0];
 
     // parse args
-    mp_arg_parse_val_t vals[PYB_SPI_RECV_NUM_ARGS];
-    mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_SPI_RECV_NUM_ARGS, pyb_spi_recv_accepted_args, vals);
+    mp_arg_val_t vals[PYB_SPI_RECV_NUM_ARGS];
+    mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_SPI_RECV_NUM_ARGS, pyb_spi_recv_args, vals);
 
     // get the buffer to receive into
     mp_buffer_info_t bufinfo;
@@ -363,12 +363,12 @@ STATIC mp_obj_t pyb_spi_recv(uint n_args, const mp_obj_t *args, mp_map_t *kw_arg
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_spi_recv_obj, 1, pyb_spi_recv);
 
-STATIC const mp_arg_parse_t pyb_spi_send_recv_accepted_args[] = {
-    { MP_QSTR_send,    MP_ARG_PARSE_REQUIRED | MP_ARG_PARSE_OBJ, {.u_obj = MP_OBJ_NULL} },
-    { MP_QSTR_recv,    MP_ARG_PARSE_OBJ, {.u_obj = MP_OBJ_NULL} },
-    { MP_QSTR_timeout, MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT, {.u_int = 5000} },
+STATIC const mp_arg_t pyb_spi_send_recv_args[] = {
+    { MP_QSTR_send,    MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+    { MP_QSTR_recv,    MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+    { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 5000} },
 };
-#define PYB_SPI_SEND_RECV_NUM_ARGS ARRAY_SIZE(pyb_spi_send_recv_accepted_args)
+#define PYB_SPI_SEND_RECV_NUM_ARGS ARRAY_SIZE(pyb_spi_send_recv_args)
 
 STATIC mp_obj_t pyb_spi_send_recv(uint n_args, const mp_obj_t *args, mp_map_t *kw_args) {
     // TODO assumes transmission size is 8-bits wide
@@ -376,8 +376,8 @@ STATIC mp_obj_t pyb_spi_send_recv(uint n_args, const mp_obj_t *args, mp_map_t *k
     pyb_spi_obj_t *self = args[0];
 
     // parse args
-    mp_arg_parse_val_t vals[PYB_SPI_SEND_RECV_NUM_ARGS];
-    mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_SPI_SEND_RECV_NUM_ARGS, pyb_spi_send_recv_accepted_args, vals);
+    mp_arg_val_t vals[PYB_SPI_SEND_RECV_NUM_ARGS];
+    mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_SPI_SEND_RECV_NUM_ARGS, pyb_spi_send_recv_args, vals);
 
     // get buffers to send from/receive to
     mp_buffer_info_t bufinfo_send;
diff --git a/stmhal/timer.c b/stmhal/timer.c
index 8a0d3f5bb6..1578e9b1d9 100644
--- a/stmhal/timer.c
+++ b/stmhal/timer.c
@@ -173,19 +173,19 @@ STATIC void pyb_timer_print(void (*print)(void *env, const char *fmt, ...), void
     }
 }
 
-STATIC const mp_arg_parse_t pyb_timer_init_accepted_args[] = {
-    { MP_QSTR_freq,      MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT, {.u_int = 0xffffffff} },
-    { MP_QSTR_prescaler, MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT, {.u_int = 0xffffffff} },
-    { MP_QSTR_period,    MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT, {.u_int = 0xffffffff} },
-    { MP_QSTR_mode,      MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT, {.u_int = TIM_COUNTERMODE_UP} },
-    { MP_QSTR_div,       MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT, {.u_int = TIM_CLOCKDIVISION_DIV1} },
+STATIC const mp_arg_t pyb_timer_init_args[] = {
+    { MP_QSTR_freq,      MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0xffffffff} },
+    { MP_QSTR_prescaler, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0xffffffff} },
+    { MP_QSTR_period,    MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0xffffffff} },
+    { MP_QSTR_mode,      MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = TIM_COUNTERMODE_UP} },
+    { MP_QSTR_div,       MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = TIM_CLOCKDIVISION_DIV1} },
 };
-#define PYB_TIMER_INIT_NUM_ARGS ARRAY_SIZE(pyb_timer_init_accepted_args)
+#define PYB_TIMER_INIT_NUM_ARGS ARRAY_SIZE(pyb_timer_init_args)
 
 STATIC mp_obj_t pyb_timer_init_helper(pyb_timer_obj_t *self, uint n_args, const mp_obj_t *args, mp_map_t *kw_args) {
     // parse args
-    mp_arg_parse_val_t vals[PYB_TIMER_INIT_NUM_ARGS];
-    mp_arg_parse_all(n_args, args, kw_args, PYB_TIMER_INIT_NUM_ARGS, pyb_timer_init_accepted_args, vals);
+    mp_arg_val_t vals[PYB_TIMER_INIT_NUM_ARGS];
+    mp_arg_parse_all(n_args, args, kw_args, PYB_TIMER_INIT_NUM_ARGS, pyb_timer_init_args, vals);
 
     // set the TIM configuration values
     TIM_Base_InitTypeDef *init = &self->tim.Init;
diff --git a/stmhal/uart.c b/stmhal/uart.c
index 66997ce3e9..a31de44f8e 100644
--- a/stmhal/uart.c
+++ b/stmhal/uart.c
@@ -225,18 +225,18 @@ STATIC void pyb_uart_print(void (*print)(void *env, const char *fmt, ...), void
     }
 }
 
-STATIC const mp_arg_parse_t pyb_uart_init_accepted_args[] = {
-    { MP_QSTR_baudrate, MP_ARG_PARSE_REQUIRED | MP_ARG_PARSE_INT, {.u_int = 9600} },
-    { MP_QSTR_bits,     MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT,  {.u_int = 8} },
-    { MP_QSTR_stop,     MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT,  {.u_int = 1} },
-    { MP_QSTR_parity,   MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_OBJ,  {.u_obj = mp_const_none} },
+STATIC const mp_arg_t pyb_uart_init_args[] = {
+    { MP_QSTR_baudrate, MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 9600} },
+    { MP_QSTR_bits,     MP_ARG_KW_ONLY | MP_ARG_INT,  {.u_int = 8} },
+    { MP_QSTR_stop,     MP_ARG_KW_ONLY | MP_ARG_INT,  {.u_int = 1} },
+    { MP_QSTR_parity,   MP_ARG_KW_ONLY | MP_ARG_OBJ,  {.u_obj = mp_const_none} },
 };
-#define PYB_UART_INIT_NUM_ARGS ARRAY_SIZE(pyb_uart_init_accepted_args)
+#define PYB_UART_INIT_NUM_ARGS ARRAY_SIZE(pyb_uart_init_args)
 
 STATIC mp_obj_t pyb_uart_init_helper(pyb_uart_obj_t *self, uint n_args, const mp_obj_t *args, mp_map_t *kw_args) {
     // parse args
-    mp_arg_parse_val_t vals[PYB_UART_INIT_NUM_ARGS];
-    mp_arg_parse_all(n_args, args, kw_args, PYB_UART_INIT_NUM_ARGS, pyb_uart_init_accepted_args, vals);
+    mp_arg_val_t vals[PYB_UART_INIT_NUM_ARGS];
+    mp_arg_parse_all(n_args, args, kw_args, PYB_UART_INIT_NUM_ARGS, pyb_uart_init_args, vals);
 
     // set the UART configuration values
     memset(&self->uart, 0, sizeof(self->uart));
@@ -327,11 +327,11 @@ STATIC mp_obj_t pyb_uart_any(mp_obj_t self_in) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_uart_any_obj, pyb_uart_any);
 
-STATIC const mp_arg_parse_t pyb_uart_send_accepted_args[] = {
-    { MP_QSTR_send,    MP_ARG_PARSE_REQUIRED | MP_ARG_PARSE_OBJ, {.u_obj = MP_OBJ_NULL} },
-    { MP_QSTR_timeout, MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT, {.u_int = 5000} },
+STATIC const mp_arg_t pyb_uart_send_args[] = {
+    { MP_QSTR_send,    MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+    { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 5000} },
 };
-#define PYB_UART_SEND_NUM_ARGS ARRAY_SIZE(pyb_uart_send_accepted_args)
+#define PYB_UART_SEND_NUM_ARGS ARRAY_SIZE(pyb_uart_send_args)
 
 STATIC mp_obj_t pyb_uart_send(uint n_args, const mp_obj_t *args, mp_map_t *kw_args) {
     // TODO assumes transmission size is 8-bits wide
@@ -339,8 +339,8 @@ STATIC mp_obj_t pyb_uart_send(uint n_args, const mp_obj_t *args, mp_map_t *kw_ar
     pyb_uart_obj_t *self = args[0];
 
     // parse args
-    mp_arg_parse_val_t vals[PYB_UART_SEND_NUM_ARGS];
-    mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_UART_SEND_NUM_ARGS, pyb_uart_send_accepted_args, vals);
+    mp_arg_val_t vals[PYB_UART_SEND_NUM_ARGS];
+    mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_UART_SEND_NUM_ARGS, pyb_uart_send_args, vals);
 
     // get the buffer to send from
     mp_buffer_info_t bufinfo;
@@ -359,11 +359,11 @@ STATIC mp_obj_t pyb_uart_send(uint n_args, const mp_obj_t *args, mp_map_t *kw_ar
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_uart_send_obj, 1, pyb_uart_send);
 
-STATIC const mp_arg_parse_t pyb_uart_recv_accepted_args[] = {
-    { MP_QSTR_recv,    MP_ARG_PARSE_REQUIRED | MP_ARG_PARSE_OBJ, {.u_obj = MP_OBJ_NULL} },
-    { MP_QSTR_timeout, MP_ARG_PARSE_KW_ONLY | MP_ARG_PARSE_INT, {.u_int = 5000} },
+STATIC const mp_arg_t pyb_uart_recv_args[] = {
+    { MP_QSTR_recv,    MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+    { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 5000} },
 };
-#define PYB_UART_RECV_NUM_ARGS ARRAY_SIZE(pyb_uart_recv_accepted_args)
+#define PYB_UART_RECV_NUM_ARGS ARRAY_SIZE(pyb_uart_recv_args)
 
 STATIC mp_obj_t pyb_uart_recv(uint n_args, const mp_obj_t *args, mp_map_t *kw_args) {
     // TODO assumes transmission size is 8-bits wide
@@ -371,8 +371,8 @@ STATIC mp_obj_t pyb_uart_recv(uint n_args, const mp_obj_t *args, mp_map_t *kw_ar
     pyb_uart_obj_t *self = args[0];
 
     // parse args
-    mp_arg_parse_val_t vals[PYB_UART_RECV_NUM_ARGS];
-    mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_UART_RECV_NUM_ARGS, pyb_uart_recv_accepted_args, vals);
+    mp_arg_val_t vals[PYB_UART_RECV_NUM_ARGS];
+    mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_UART_RECV_NUM_ARGS, pyb_uart_recv_args, vals);
 
     // get the buffer to receive into
     mp_buffer_info_t bufinfo;