zephyr: Enable sys.stdin/out/err.

This change enables `sys.stdin`, `sys.stdout` and `sys.stderr` objects.
They are useful for general IO, and also help with testing zephyr boards.

Signed-off-by: Damien George <damien@micropython.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/ports/zephyr/src/zephyr_getchar.c b/ports/zephyr/src/zephyr_getchar.c
index 94e35e2e8..7660e3cc1 100644
--- a/ports/zephyr/src/zephyr_getchar.c
+++ b/ports/zephyr/src/zephyr_getchar.c
@@ -49,6 +49,11 @@ static int console_irq_input_hook(uint8_t ch) {
     return 1;
 }
 
+// Returns true if a char is available for reading.
+int zephyr_getchar_check(void) {
+    return i_get != i_put;
+}
+
 int zephyr_getchar(void) {
     mp_hal_wait_sem(&uart_sem, 0);
     if (k_sem_take(&uart_sem, K_MSEC(0)) == 0) {