esp32/machine_uart: Increase UART TX buffer size to 64.

This is the minimum size that the TX buffer allows.  Any smaller and it
loses the first 2 characters that are sent.

Author: dpgeorge

esp32/machine_uart.c

@@ -237,8 +237,8 @@ STATIC mp_obj_t machine_uart_make_new(const mp_obj_type_t *type, size_t n_args,
     // Setup
     uart_param_config(self->uart_num, &uartcfg);
 
-    // RX and TX buffers are currently hardcoded at 256 and 32 bytes respectively.
-    uart_driver_install(uart_num, 256, 32, 10, &UART_QUEUE[self->uart_num], 0);
+    // RX and TX buffers are currently hardcoded at 256 and 64 bytes respectively.
+    uart_driver_install(uart_num, 256, 64, 10, &UART_QUEUE[self->uart_num], 0);
 
     mp_map_t kw_args;
     mp_map_init_fixed_table(&kw_args, n_kw, args + n_args);