Short answers, pulled from the story.
British Prime Minister Ramsay MacDonald announced the Communal Award on the 16th of August 1932. This decision followed the failure of the Second Round Table Conference held between 1930 and 1932.
The award extended separate electorates to Muslims, Sikhs, Indian Christians, Anglo-Indians, Europeans, and Depressed Classes. Previous laws had introduced these systems for Muslims in 1909 and expanded them for other minorities in 1919.
Mahatma Gandhi reacted with immediate anger to the Communal Award announced on the 16th of August 1932. He declared an open fast unto death from Yervada Jail in September 1932 to oppose the policy.
Gandhi reached an agreement with Ambedkar to replace the Communal Award provisions with reserved seats through the Poona Pact. They established a single Hindu electorate while ensuring specific seats remained set aside for Scheduled Castes.
B. R. Ambedkar insisted on separate electorates for Scheduled Castes because he believed that without voting rights they would remain subjugated within the Hindu fold. He argued that Gandhi was ready to grant separate representation to Muslims and Sikhs but refused it for Untouchables.