diff --git a/ports/stm32/pyb_i2c.c b/ports/stm32/pyb_i2c.c
index f0bd38333..dbcf4bcb8 100644
--- a/ports/stm32/pyb_i2c.c
+++ b/ports/stm32/pyb_i2c.c
@@ -49,14 +49,14 @@
 ///     from pyb import I2C
 ///
 ///     i2c = I2C(1)                         # create on bus 1
-///     i2c = I2C(1, I2C.MASTER)             # create and init as a master
-///     i2c.init(I2C.MASTER, baudrate=20000) # init as a master
-///     i2c.init(I2C.SLAVE, addr=0x42)       # init as a slave with given address
-///     i2c.deinit()                         # turn off the peripheral
+///     i2c = I2C(1, I2C.CONTROLLER)         # create and init as a controller
+///     i2c.init(I2C.CONTROLLER, baudrate=20000) # init as a controller
+///     i2c.init(I2C.PERIPHERAL, addr=0x42)  # init as a peripheral with given address
+///     i2c.deinit()                         # turn off the I2C unit
 ///
 /// Printing the i2c object gives you information about its configuration.
 ///
-/// Basic methods for slave are send and recv:
+/// Basic methods for peripheral are send and recv:
 ///
 ///     i2c.send('abc')      # send 3 bytes
 ///     i2c.send(0x42)       # send a single byte, given by the number
@@ -71,19 +71,19 @@
 ///
 ///     i2c.send(b'123', timeout=2000)   # timout after 2 seconds
 ///
-/// A master must specify the recipient's address:
+/// A controller must specify the recipient's address:
 ///
-///     i2c.init(I2C.MASTER)
-///     i2c.send('123', 0x42)        # send 3 bytes to slave with address 0x42
+///     i2c.init(I2C.CONTROLLER)
+///     i2c.send('123', 0x42)        # send 3 bytes to peripheral with address 0x42
 ///     i2c.send(b'456', addr=0x42)  # keyword for address
 ///
 /// Master also has other methods:
 ///
-///     i2c.is_ready(0x42)           # check if slave 0x42 is ready
-///     i2c.scan()                   # scan for slaves on the bus, returning
+///     i2c.is_ready(0x42)           # check if peripheral 0x42 is ready
+///     i2c.scan()                   # scan for peripherals on the bus, returning
 ///                                  #   a list of valid addresses
-///     i2c.mem_read(3, 0x42, 2)     # read 3 bytes from memory of slave 0x42,
-///                                  #   starting at address 2 in the slave
+///     i2c.mem_read(3, 0x42, 2)     # read 3 bytes from memory of peripheral 0x42,
+///                                  #   starting at address 2 in the peripheral
 ///     i2c.mem_write('abc', 0x42, 2, timeout=1000)
 #define PYB_I2C_MASTER (0)
 #define PYB_I2C_SLAVE  (1)
@@ -578,7 +578,7 @@ STATIC void pyb_i2c_print(const mp_print_t *print, mp_obj_t self_in, mp_print_ki
         mp_printf(print, "I2C(%u)", i2c_num);
     } else {
         if (in_master_mode(self)) {
-            mp_printf(print, "I2C(%u, I2C.MASTER, baudrate=%u"
+            mp_printf(print, "I2C(%u, I2C.CONTROLLER, baudrate=%u"
                 #if PYB_I2C_TIMINGR
                 ", timingr=0x%08x"
                 #endif
@@ -588,7 +588,7 @@ STATIC void pyb_i2c_print(const mp_print_t *print, mp_obj_t self_in, mp_print_ki
                 #endif
                 );
         } else {
-            mp_printf(print, "I2C(%u, I2C.SLAVE, addr=0x%02x)", i2c_num, (self->i2c->Instance->OAR1 >> 1) & 0x7f);
+            mp_printf(print, "I2C(%u, I2C.PERIPHERAL, addr=0x%02x)", i2c_num, (self->i2c->Instance->OAR1 >> 1) & 0x7f);
         }
     }
 }
@@ -597,9 +597,9 @@ STATIC void pyb_i2c_print(const mp_print_t *print, mp_obj_t self_in, mp_print_ki
 ///
 /// Initialise the I2C bus with the given parameters:
 ///
-///   - `mode` must be either `I2C.MASTER` or `I2C.SLAVE`
-///   - `addr` is the 7-bit address (only sensible for a slave)
-///   - `baudrate` is the SCL clock rate (only sensible for a master)
+///   - `mode` must be either `I2C.CONTROLLER` or `I2C.PERIPHERAL`
+///   - `addr` is the 7-bit address (only sensible for a peripheral)
+///   - `baudrate` is the SCL clock rate (only sensible for a controller)
 ///   - `gencall` is whether to support general call mode
 STATIC mp_obj_t pyb_i2c_init_helper(const pyb_i2c_obj_t *self, size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
     static const mp_arg_t allowed_args[] = {
@@ -621,7 +621,7 @@ STATIC mp_obj_t pyb_i2c_init_helper(const pyb_i2c_obj_t *self, size_t n_args, co
     I2C_InitTypeDef *init = &self->i2c->Init;
 
     if (args[0].u_int == PYB_I2C_MASTER) {
-        // use a special address to indicate we are a master
+        // use a special address to indicate we are a controller
         init->OwnAddress1 = PYB_I2C_MASTER_ADDRESS;
     } else {
         init->OwnAddress1 = (args[1].u_int << 1) & 0xfe;
@@ -697,12 +697,12 @@ STATIC mp_obj_t pyb_i2c_deinit(mp_obj_t self_in) {
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_i2c_deinit_obj, pyb_i2c_deinit);
 
 /// \method is_ready(addr)
-/// Check if an I2C device responds to the given address.  Only valid when in master mode.
+/// Check if an I2C device responds to the given address.  Only valid when in controller mode.
 STATIC mp_obj_t pyb_i2c_is_ready(mp_obj_t self_in, mp_obj_t i2c_addr_o) {
     pyb_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
 
     if (!in_master_mode(self)) {
-        mp_raise_TypeError(MP_ERROR_TEXT("I2C must be a master"));
+        mp_raise_TypeError(MP_ERROR_TEXT("I2C must be a controller"));
     }
 
     mp_uint_t i2c_addr = mp_obj_get_int(i2c_addr_o) << 1;
@@ -720,12 +720,12 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_2(pyb_i2c_is_ready_obj, pyb_i2c_is_ready);
 
 /// \method scan()
 /// Scan all I2C addresses from 0x08 to 0x77 and return a list of those that respond.
-/// Only valid when in master mode.
+/// Only valid when in controller mode.
 STATIC mp_obj_t pyb_i2c_scan(mp_obj_t self_in) {
     pyb_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
 
     if (!in_master_mode(self)) {
-        mp_raise_TypeError(MP_ERROR_TEXT("I2C must be a master"));
+        mp_raise_TypeError(MP_ERROR_TEXT("I2C must be a controller"));
     }
 
     mp_obj_t list = mp_obj_new_list(0, NULL);
@@ -745,7 +745,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_i2c_scan_obj, pyb_i2c_scan);
 /// Send data on the bus:
 ///
 ///   - `send` is the data to send (an integer to send, or a buffer object)
-///   - `addr` is the address to send to (only required in master mode)
+///   - `addr` is the address to send to (only required in controller mode)
 ///   - `timeout` is the timeout in milliseconds to wait for the send
 ///
 /// Return value: `None`.
@@ -824,7 +824,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_i2c_send_obj, 1, pyb_i2c_send);
 ///
 ///   - `recv` can be an integer, which is the number of bytes to receive,
 ///     or a mutable buffer, which will be filled with received bytes
-///   - `addr` is the address to receive from (only required in master mode)
+///   - `addr` is the address to receive from (only required in controller mode)
 ///   - `timeout` is the timeout in milliseconds to wait for the receive
 ///
 /// Return value: if `recv` is an integer then a new buffer of the bytes received,
@@ -910,7 +910,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_i2c_recv_obj, 1, pyb_i2c_recv);
 ///   - `addr_size` selects width of memaddr: 8 or 16 bits
 ///
 /// Returns the read data.
-/// This is only valid in master mode.
+/// This is only valid in controller mode.
 STATIC const mp_arg_t pyb_i2c_mem_read_allowed_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} },
@@ -926,7 +926,7 @@ STATIC mp_obj_t pyb_i2c_mem_read(size_t n_args, const mp_obj_t *pos_args, mp_map
     mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(pyb_i2c_mem_read_allowed_args), pyb_i2c_mem_read_allowed_args, args);
 
     if (!in_master_mode(self)) {
-        mp_raise_TypeError(MP_ERROR_TEXT("I2C must be a master"));
+        mp_raise_TypeError(MP_ERROR_TEXT("I2C must be a controller"));
     }
 
     // get the buffer to read into
@@ -986,7 +986,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_i2c_mem_read_obj, 1, pyb_i2c_mem_read);
 ///   - `addr_size` selects width of memaddr: 8 or 16 bits
 ///
 /// Returns `None`.
-/// This is only valid in master mode.
+/// This is only valid in controller mode.
 STATIC mp_obj_t pyb_i2c_mem_write(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
     // parse args (same as mem_read)
     pyb_i2c_obj_t *self = MP_OBJ_TO_PTR(pos_args[0]);
@@ -994,7 +994,7 @@ STATIC mp_obj_t pyb_i2c_mem_write(size_t n_args, const mp_obj_t *pos_args, mp_ma
     mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(pyb_i2c_mem_read_allowed_args), pyb_i2c_mem_read_allowed_args, args);
 
     if (!in_master_mode(self)) {
-        mp_raise_TypeError(MP_ERROR_TEXT("I2C must be a master"));
+        mp_raise_TypeError(MP_ERROR_TEXT("I2C must be a controller"));
     }
 
     // get the buffer to write from
@@ -1051,8 +1051,11 @@ STATIC const mp_rom_map_elem_t pyb_i2c_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_mem_write), MP_ROM_PTR(&pyb_i2c_mem_write_obj) },
 
     // class constants
-    /// \constant MASTER - for initialising the bus to master mode
-    /// \constant SLAVE - for initialising the bus to slave mode
+    /// \constant CONTROLLER - for initialising the bus to controller mode
+    /// \constant PERIPHERAL - for initialising the bus to peripheral mode
+    { MP_ROM_QSTR(MP_QSTR_CONTROLLER), MP_ROM_INT(PYB_I2C_MASTER) },
+    { MP_ROM_QSTR(MP_QSTR_PERIPHERAL),  MP_ROM_INT(PYB_I2C_SLAVE) },
+    // TODO - remove MASTER/SLAVE when CONTROLLER/PERIPHERAL gain wide adoption
     { MP_ROM_QSTR(MP_QSTR_MASTER), MP_ROM_INT(PYB_I2C_MASTER) },
     { MP_ROM_QSTR(MP_QSTR_SLAVE), MP_ROM_INT(PYB_I2C_SLAVE) },
 };
diff --git a/ports/stm32/pyb_spi.c b/ports/stm32/pyb_spi.c
index 99a1cd77b..abb7ba41d 100644
--- a/ports/stm32/pyb_spi.c
+++ b/ports/stm32/pyb_spi.c
@@ -32,18 +32,18 @@
 /******************************************************************************/
 // MicroPython bindings for legacy pyb API
 
-// class pyb.SPI - a master-driven serial protocol
+// class pyb.SPI - a controller-driven serial protocol
 //
-// SPI is a serial protocol that is driven by a master.  At the physical level
+// SPI is a serial protocol that is driven by a controller.  At the physical level
 // there are 3 lines: SCK, MOSI, MISO.
 //
 // See usage model of I2C; SPI is very similar.  Main difference is
 // parameters to init the SPI bus:
 //
 //     from pyb import SPI
-//     spi = SPI(1, SPI.MASTER, baudrate=600000, polarity=1, phase=0, crc=0x7)
+//     spi = SPI(1, SPI.CONTROLLER, baudrate=600000, polarity=1, phase=0, crc=0x7)
 //
-// Only required parameter is mode, SPI.MASTER or SPI.SLAVE.  Polarity can be
+// Only required parameter is mode, SPI.CONTROLLER or SPI.PERIPHERAL.  Polarity can be
 // 0 or 1, and is the level the idle clock line sits at.  Phase can be 0 or 1
 // to sample data on the first or second clock edge respectively.  Crc can be
 // None for no CRC, or a polynomial specifier.
@@ -72,8 +72,8 @@ STATIC void pyb_spi_print(const mp_print_t *print, mp_obj_t self_in, mp_print_ki
 // init(mode, baudrate=328125, *, polarity=1, phase=0, bits=8, firstbit=SPI.MSB, ti=False, crc=None)
 //
 // Initialise the SPI bus with the given parameters:
-//   - `mode` must be either `SPI.MASTER` or `SPI.SLAVE`.
-//   - `baudrate` is the SCK clock rate (only sensible for a master).
+//   - `mode` must be either `SPI.CONTROLLER` or `SPI.PERIPHERAL`.
+//   - `baudrate` is the SCK clock rate (only sensible for a controller).
 STATIC mp_obj_t pyb_spi_init_helper(const pyb_spi_obj_t *self, size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_mode,     MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 0} },
@@ -319,10 +319,13 @@ STATIC const mp_rom_map_elem_t pyb_spi_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_send_recv), MP_ROM_PTR(&pyb_spi_send_recv_obj) },
 
     // class constants
-    /// \constant MASTER - for initialising the bus to master mode
-    /// \constant SLAVE - for initialising the bus to slave mode
+    /// \constant CONTROLLER - for initialising the bus to controller mode
+    /// \constant PERIPHERAL - for initialising the bus to peripheral mode
     /// \constant MSB - set the first bit to MSB
     /// \constant LSB - set the first bit to LSB
+    { MP_ROM_QSTR(MP_QSTR_CONTROLLER), MP_ROM_INT(SPI_MODE_MASTER) },
+    { MP_ROM_QSTR(MP_QSTR_PERIPHERAL),  MP_ROM_INT(SPI_MODE_SLAVE) },
+    // TODO - remove MASTER/SLAVE when CONTROLLER/PERIPHERAL gain wide adoption
     { MP_ROM_QSTR(MP_QSTR_MASTER), MP_ROM_INT(SPI_MODE_MASTER) },
     { MP_ROM_QSTR(MP_QSTR_SLAVE),  MP_ROM_INT(SPI_MODE_SLAVE) },
     { MP_ROM_QSTR(MP_QSTR_MSB),    MP_ROM_INT(SPI_FIRSTBIT_MSB) },
diff --git a/ports/stm32/spi.c b/ports/stm32/spi.c
index d3b3a784e..0ce6b5abc 100644
--- a/ports/stm32/spi.c
+++ b/ports/stm32/spi.c
@@ -640,14 +640,14 @@ void spi_print(const mp_print_t *print, const spi_t *spi_obj, bool legacy) {
             #endif
             uint baudrate = spi_get_source_freq(spi) >> log_prescaler;
             if (legacy) {
-                mp_printf(print, ", SPI.MASTER");
+                mp_printf(print, ", SPI.CONTROLLER");
             }
             mp_printf(print, ", baudrate=%u", baudrate);
             if (legacy) {
                 mp_printf(print, ", prescaler=%u", 1 << log_prescaler);
             }
         } else {
-            mp_printf(print, ", SPI.SLAVE");
+            mp_printf(print, ", SPI.PERIPHERAL");
         }
         mp_printf(print, ", polarity=%u, phase=%u, bits=%u", spi->Init.CLKPolarity == SPI_POLARITY_LOW ? 0 : 1, spi->Init.CLKPhase == SPI_PHASE_1EDGE ? 0 : 1, spi->Init.DataSize == SPI_DATASIZE_8BIT ? 8 : 16);
         if (spi->Init.CRCCalculation == SPI_CRCCALCULATION_ENABLE) {
diff --git a/tests/pyb/i2c.py b/tests/pyb/i2c.py
index bc9dba878..c96884327 100644
--- a/tests/pyb/i2c.py
+++ b/tests/pyb/i2c.py
@@ -11,6 +11,6 @@ for bus in (-1, 0, 1):
 
 i2c = I2C(1)
 
-i2c.init(I2C.MASTER, baudrate=400000)
+i2c.init(I2C.CONTROLLER, baudrate=400000)
 print(i2c.scan())
 i2c.deinit()
diff --git a/tests/pyb/i2c_accel.py b/tests/pyb/i2c_accel.py
index 8c74fa60e..8b87d406d 100644
--- a/tests/pyb/i2c_accel.py
+++ b/tests/pyb/i2c_accel.py
@@ -11,7 +11,7 @@ accel_addr = 76
 
 pyb.Accel()  # this will init the MMA for us
 
-i2c = I2C(1, I2C.MASTER, baudrate=400000)
+i2c = I2C(1, I2C.CONTROLLER, baudrate=400000)
 
 print(i2c.scan())
 print(i2c.is_ready(accel_addr))
diff --git a/tests/pyb/i2c_error.py b/tests/pyb/i2c_error.py
index b17a26325..1228962f5 100644
--- a/tests/pyb/i2c_error.py
+++ b/tests/pyb/i2c_error.py
@@ -11,7 +11,7 @@ if not hasattr(pyb, "Accel"):
 pyb.Accel()
 
 # get I2C bus
-i2c = I2C(1, I2C.MASTER, dma=True)
+i2c = I2C(1, I2C.CONTROLLER, dma=True)
 
 # test polling mem_read
 pyb.disable_irq()
diff --git a/tests/pyb/pyb_f405.py b/tests/pyb/pyb_f405.py
index 243381056..d7431a11a 100644
--- a/tests/pyb/pyb_f405.py
+++ b/tests/pyb/pyb_f405.py
@@ -10,7 +10,7 @@ print(pyb.freq())
 print(type(pyb.rng()))
 
 # test HAL error specific to F405
-i2c = pyb.I2C(2, pyb.I2C.MASTER)
+i2c = pyb.I2C(2, pyb.I2C.CONTROLLER)
 try:
     i2c.recv(1, 1)
 except OSError as e:
diff --git a/tests/pyb/spi.py b/tests/pyb/spi.py
index 73d39e724..7df6aeb45 100644
--- a/tests/pyb/spi.py
+++ b/tests/pyb/spi.py
@@ -11,12 +11,14 @@ for bus in (-1, 0, 1, 2):
 spi = SPI(1)
 print(spi)
 
-spi = SPI(1, SPI.MASTER)
-spi = SPI(1, SPI.MASTER, baudrate=500000)
-spi = SPI(1, SPI.MASTER, 500000, polarity=1, phase=0, bits=8, firstbit=SPI.MSB, ti=False, crc=None)
-print(str(spi)[:28], str(spi)[49:])  # don't print baudrate/prescaler
+spi = SPI(1, SPI.CONTROLLER)
+spi = SPI(1, SPI.CONTROLLER, baudrate=500000)
+spi = SPI(
+    1, SPI.CONTROLLER, 500000, polarity=1, phase=0, bits=8, firstbit=SPI.MSB, ti=False, crc=None
+)
+print(str(spi)[:32], str(spi)[53:])  # don't print baudrate/prescaler
 
-spi.init(SPI.SLAVE, phase=1)
+spi.init(SPI.PERIPHERAL, phase=1)
 print(spi)
 try:
     # need to flush input before we get an error (error is what we want to test)
@@ -25,7 +27,7 @@ try:
 except OSError:
     print("OSError")
 
-spi.init(SPI.MASTER)
+spi.init(SPI.CONTROLLER)
 spi.send(1, timeout=100)
 print(spi.recv(1, timeout=100))
 print(spi.send_recv(1, timeout=100))
diff --git a/tests/pyb/spi.py.exp b/tests/pyb/spi.py.exp
index 473c173a5..661bace90 100644
--- a/tests/pyb/spi.py.exp
+++ b/tests/pyb/spi.py.exp
@@ -3,8 +3,8 @@ ValueError 0
 SPI 1
 SPI 2
 SPI(1)
-SPI(1, SPI.MASTER, baudrate= , polarity=1, phase=0, bits=8)
-SPI(1, SPI.SLAVE, polarity=1, phase=1, bits=8)
+SPI(1, SPI.CONTROLLER, baudrate= , polarity=1, phase=0, bits=8)
+SPI(1, SPI.PERIPHERAL, polarity=1, phase=1, bits=8)
 OSError
 b'\xff'
 b'\xff'