diff options
| author | David Hendricks <dhendrix@chromium.org> | 2012-08-20 18:37:27 -0700 |
|---|---|---|
| committer | Gerrit <chrome-bot@google.com> | 2012-08-21 14:14:47 -0700 |
| commit | 31d9a1294e11e554c704d515b6752b81da934e1c (patch) | |
| tree | fc6648926af721db4db16d16be1912bdcccc030d /board | |
| parent | ede77d7cac6a9730f706cb110da414748b45379e (diff) | |
| download | chrome-ec-31d9a1294e11e554c704d515b6752b81da934e1c.tar.gz | |
snow: configure USART Rx as an input with pull resistor
USART1 has always had its Tx and Rx pins configured as "alternate
function output". However, this turns out to be incorrect since
there is no concept of an AF input on the STM32F. Instead, the
Rx pin should be configured as an input (and the Tx remains an
AF output).
This also simplifies the console resume code since we only need to
enable/disable the interrupt rather than reconfiguring the GPIO.
Signed-off-by: David Hendricks <dhendrix@chromium.org>
BRANCH=snow
BUG=chrome-os-partner:12223
TEST=flashed on snow, EC console works
Change-Id: Ia92dbbac16fc55d0db62381dfb487aeb4f4121b4
Reviewed-on: https://gerrit.chromium.org/gerrit/30941
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
Commit-Ready: David Hendricks <dhendrix@chromium.org>
Tested-by: David Hendricks <dhendrix@chromium.org>
Diffstat (limited to 'board')
| -rw-r--r-- | board/snow/board.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/board/snow/board.c b/board/snow/board.c index b612955af3..258b534184 100644 --- a/board/snow/board.c +++ b/board/snow/board.c @@ -123,9 +123,17 @@ void configure_board(void) STM32_GPIO_BSRR_OFF(GPIO_B) |= (1<<11) | (1<<10) | (1<<7) | (1<<6); - /* Select Alternate function for USART1 on pins PA9/PA10 */ + /* + * Set alternate function for USART1. For alt. function input + * the port is configured in either floating or pull-up/down + * input mode (ref. section 7.1.4 in datasheet RM0041): + * PA9: Tx, alt. function output + * PA10: Rx, input with pull-down + * + * note: see crosbug.com/p/12223 for more info + */ val = STM32_GPIO_CRH_OFF(GPIO_A) & ~0x00000ff0; - val |= 0x00000990; + val |= 0x00000890; STM32_GPIO_CRH_OFF(GPIO_A) = val; /* EC_INT is output, open-drain */ |